Anti-double Stranded DNA Antibodies: Origin, Pathogenicity, and Targeted Therapies

Clinical correlations of serum anti-dsDNA immunoglobulin subfamilies in patients with systemic lupus erythematosus (SLE)

Systemic lupus erythematosus (SLE) is an extremely heterogenous autoimmune disorder. A key biomarker, the double stranded (ds) DNA autoantibody, provides diagnostic specificity for SLE. We analyzed anti-dsDNA by mass spectrometry (MS) to determine if ascertaining the autoantibody's heavy chain variable region (IGHV) may hold any clinical relevance. A cross-sectional study of 32 SLE patients (75% female) in a single center was performed. Serum anti-dsDNA was subjected to MS analyses. Obtained IGHV subfamilies were correlated with active clinical features of SLE, as determined by medical record reviews. We established significant associations with the presence of IGHV3-15 and active neuropsychiatric lupus (relative risk [RR] 5.71); IGHV3-21, IGHV3-23 and IGHV4-34 and leukopenia (RR 13.70, 2.14 and 10.29 respectively); and IGHV3-23 and serositis (RR 2.41) and cutaneous lesions (RR 2.82). This study provides the first evidence for the clinical benefits of deep anti-dsDNA profiling through MS, and provides an avenue for improving predictive medicine for SLE patients. Future studies with a greater number of patients, and to determine if these subfamilies have direct pathogenic properties are required.

Autoantibodies in systemic sclerosis: From disease bystanders to pathogenic players

Autoantibodies (Aab) are recognized as key indicators in the diagnosis, classification, and monitoring of systemic autoimmune diseases (AID). Recent studies have expanded knowledge through the discovery of new antigenic targets, advanced methods for measuring Aab levels, and understanding their possible pathogenic roles in AID. This narrative review uses systemic sclerosis (SSc) as an example to highlight the importance of Aab associated with HEp-2 immunofluorescence assay positivity (traditionally referred as antinuclear antibodies [ANA]), exploring recent developments in the field. Firstly, we outline the various types of ANA found in SSc and their links with specific disease features. Newly discovered antibodies shed light on SSc cases where Aab had previously gone unidentified. Secondly, we emphasize the necessity for novel quantitative techniques to track Aab levels over time by gathering data regarding the timing of Aab occurrence relative to SSc symptoms and the relationships between Aab concentrations and disease severity. Finally, we discuss the experimental findings suggesting a potential direct role of Aab in the development of SSc. The advancements surrounding Aab provide insights into new disease mechanisms and may lead to innovative diagnostic and treatment approaches.

A Comprehensive Review of Fc Gamma Receptors and Their Role in Systemic Lupus Erythematosus

Receptors for the immunoglobulin G constant fraction (FcγRs) are widely expressed in cells of the immune system. Complement-independent phagocytosis prompted FcγR research to show that the engagement of IgG immune complexes with FcγRs triggers a variety of cell host immune responses, such as phagocytosis, antibody-dependent cell cytotoxicity, and NETosis, among others. However, variants of these receptors have been implicated in the development of and susceptibility to autoimmune diseases such as systemic lupus erythematosus. Currently, the knowledge of FcγR variants is a required field of antibody therapeutics, which includes the engineering of recombinant soluble human Fc gamma receptors, enhancing the inhibitory and blocking the activating FcγRs function, vaccines, and organ transplantation. Importantly, recent interest in FcγRs is the antibody-dependent enhancement (ADE), a mechanism by which the pathogenesis of certain viral infections is enhanced. ADEs may be responsible for the severity of the SARS-CoV-2 infection. Therefore, FcγRs have become a current research topic. Therefore, this review briefly describes some of the historical knowledge about the FcγR type I family in humans, including the structure, affinity, and mechanism of ligand binding, FcγRs in diseases such as systemic lupus erythematosus (SLE), and the potential therapeutic approaches related to these receptors in SLE.

Single-cell transcriptomic analysis reveals distinct plasma cell populations in chronic thromboembolic pulmonary hypertension

BACKGROUND

Chronic thromboembolic pulmonary hypertension (CTEPH) presents challenges due to its complex pathobiology. Although numerous studies have reported heterogeneous cell types by single-cell RNA sequencing, the atlas and characteristics of plasma cells remain poorly understood.

OBJECTIVES

To identify the altered phenotype and differentiation patterns of plasma cells in CTEPH.

METHODS

We performed single-cell RNA sequencing on pulmonary endarterectomy tissue from 5 patients and 6 normal pulmonary arteries. Serum immunoglobulins (Igs) were measured using protein electrophoresis among 273 CTEPH patients, 259 idiopathic pulmonary arterial hypertension (IPAH) patients, and 251 healthy controls.

RESULTS

The percentage of plasma cells was significantly increased from less than 1% in healthy controls to 15% in CTEPH patients. We identified 1 B cell cluster and 5 distinct mature plasma cell clusters, including IGHG1, HSPA1A, AHNAK, IGLC3, and IGKV4. Notably, the AHNAK and IGLC3 subclusters are newly identified. GeneSwitches analysis indicated early activation of IGHG1 and early deactivation of HLA-DPA1. The trajectory of AHNAK cluster was earlier than that of IGLC3 cluster, with an enrichment for pathways responsive to lipopolysaccharide. The IGLC3 cluster revealed lower differentiation potential and was predominantly associated with Ig production. Furthermore, Igα2 levels in CTEPH patients were lower than in controls but higher than in IPAH patients. Significantly, Igγ levels were markedly elevated in CTEPH patients compared with IPAH patients and controls, better distinguishing CTEPH patients from controls and IPAH patients.

CONCLUSION

Plasma cells of CTEPH had a distinctive landscape and heterogeneity. The newly identified clusters represented excessive Ig production but lacked immune response function. These findings highlight that targeted plasma cells can be used to develop novel CTEPH treatments.

Targeting the Progression of Lupus-Like Disease in Humanized Mouse Model by Specific Dietary Components

Systemic lupus erythematosus (SLE) is a complex autoimmune disease with a number of immunological aberrations in the mechanisms of innate and adaptive immune responses. Spontaneous and induced mouse models of the disease have contributed significantly to the advancement in lupus treatments. The involvement of humanized models, engrafted with lupus patients' immune cells, represented the possibility to study the development of SLE. In the current research, we engrafted NSG/Rag2-γc- mice with PBMCs from lupus patients and put the mice on specific diet composed of extra amounts of methyl-containing micronutrients and cofactors which are key participants in the DNA methylation processes. The results showed a decrease in anti-dsDNA IgG antibody and in proteinuria levels, less glomerular proliferation and protected renal structures in all mice put on the supplemented diet compared to humanized mice fed with the control diet. The observed therapeutic effect may be related to possible alterations in the methylation level and to targeted suppression of gene expression in the immune cells, which correlate negatively with the development of the clinical SLE characteristics. These findings point to the significant immunomodulating role of methyl donors in human models of SLE and represent new therapeutic opportunities with clinical potential.

The Effect of Estradiol and Testosterone Levels Alone or in Combination with Their Receptors in Predicting the Severity of Systemic Lupus Erythematosus: A Cohort Study

Background

Developing a practical method to predict active systemic lupus erythematosus (SLE) in patients with inactive/mild status at the onset of the disease could lead to appropriate treatment that ultimately prevents future relapses. The development of SLE is influenced by steroid hormones and probably the receptors of these hormones. Therefore, we aimed to investigate the predictive effect of the levels of estradiol and testosterone hormones and their receptors on the severity of SLE disease.

Methods

Serum samples were taken from 59 female patients with inactive SLE in Golestan province in northern Iran. The concentration of estradiol (E2) and testosterone (T) hormones and their receptors, estrogen receptors (ER) and androgen receptors (AR), was measured at the beginning of the study after sampling. After a one-year follow-up (2021 to 2022), the patients were divided into active and inactive SLE groups based on the clinical criteria of the SLE activity index. T test and Mann-Whitney U-test were used to analyze the difference of variables. The correlation was analyzed using Pearson and Spearman tests. Discriminative power was measured, and a cut-off point was suggested.

Results

There was a significant difference in the average E2+ER/T+AR ratio between active and inactive SLE groups (P<0.001). It was also found that this ratio has a significant correlation with the severity of the disease (r=0.546, P<0.001).

Conclusion

Despite the normal concentration of each steroid hormone and its receptors, the E2+ER/T+AR ratio may be a good indicator of the development of active SLE.

Predictors of renal flares in systemic lupus erythematosus: a post-hoc analysis of four phase III clinical trials of belimumab

OBJECTIVE

The objective of this study was to identify predictors of renal flares in patients with SLE treated for active extra-renal disease.

METHODS

Data from four clinical trials of belimumab in SLE (BLISS-52, NCT00424476; BLISS-76, NCT00410384; BLISS-NEA, NCT01345253; BLISS-SC, NCT01484496) were used. Patients were assigned to belimumab or placebo on top of standard therapy. We investigated the performance of predictors of renal flares through weeks 52-76 using proportional hazards regression analysis.

RESULTS

Of 3225 participants, 192 developed at least one renal flare during follow-up, with the first occurring after a median time of 197 days. Current/former renal involvement [hazards ratio (HR): 15.4; 95% CI: 8.3-28.2; P < 0.001], low serum albumin levels (HR 0.9; 95% CI: 0.8-0.9; P < 0.001), proteinuria (HR: 1.6; 95% CI: 1.5-1.7; P < 0.001), and low C3 levels (HR: 2.9; 95% CI: 2.1-4.1; P < 0.001) at baseline appeared robust determinants of impending renal flares. Anti-dsDNA positivity yielded an increased hazard for renal flares (HR: 2.1; 95% CI: 1.4-3.2; P < 0.001), which attenuated after adjustments. Anti-Sm positivity was associated with renal flares in the placebo (HR: 3.7; 95% CI: 2.0-6.9; P < 0.001) but not in the belimumab subgroup, whereas anti-ribosomal P positivity was associated with renal flares in the belimumab subgroup only (HR: 2.8; 95% CI: 1.5-5.0; P = 0.001).

CONCLUSION

A history of renal involvement, high baseline proteinuria, hypoalbuminaemia, and C3 consumption were robust determinants of impending renal flares. In addition to anti-dsDNA, anti-Sm and anti-ribosomal P protein antibody positivity may have value in surveillance of renal SLE.

Application of the Monoclonal Autoantibody and Its Target Protein Derived from the Peripheral Blood of SLE Patients in Serological Diagnosis and Differential Diagnosis of SLE

INTRODUCTION

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder with limited reliable diagnostic biomarkers. This study evaluates the utility of DEAD-box helicase 5 (DDX5) as a diagnostic and differential marker for SLE and assesses the performance of a capture bead-based flow cytometry (CBFCM) method for detecting serum proteins.

METHOD

Serum samples were collected from 52 patients with SLE, 38 patients with rheumatoid arthritis (RA), 49 patients with lung cancer (LC), and 50 healthy controls (HCs). Levels of DDX5, anti-DDX5, anti-dsDNA, and anti-Sm were quantified using enzyme-linked immunosorbent assay (ELISA) and CBFCM.

RESULTS

Serum DDX5 levels were significantly elevated in patients with SLE compared to patients with RA and HCs, correlating with the SLE activity. DDX5 demonstrated strong discriminatory power between SLE and RA. Combining DDX5, anti-dsDNA, and anti-Sm as biomarkers yielded an area under the curve (AUC) of 0.976 for SLE diagnosis. Decision curve analysis indicated a high clinical benefit from the combined biomarkers. The sensitivity and specificity of DDX5 were 66.11% and 88.89% for ELISA, and 72% and 91.3% for CBFCM.

DISCUSSION

DDX5 shows promise as a novel serological biomarker for SLE diagnosis and differential diagnosis. Additionally, CBFCM outperforms ELISA in detecting soluble serum proteins.

Unravelling the TCRβ repertoire: a key to unlocking the immunopathogenesis and precision medicine in SLE

OBJECTIVES

SLE is a multifaceted autoimmune disorder with a complex pathogenesis involving genetic, environmental and hormonal factors, which converge on immune dysregulation. The T cell receptor (TCR) repertoire's role in SLE has garnered significant interest due to its potential in both diagnostics and therapeutics. Our study aimed to delineate the variances in the TCRβ repertoire between patients with SLE and healthy individuals, correlating these differences with the severity and subtypes of SLE.

METHODS

We conducted an analysis of blood samples from 50 treatment-naive patients with SLE and 50 healthy donors, employing RNA extraction, high-throughput sequencing and subsequent bioinformatics analysis.

RESULTS

Our findings revealed significant alterations in TRBV and TRBJ gene usage frequencies, indicative of a skewed TCR repertoire in patients with SLE. Notably, nine hub TRBV genes were identified as potential biomarkers for SLE with high diagnostic accuracy. Furthermore, we observed a reduction in TCR diversity, characterised by a lower diversity 50 value and increased clonal expansion, which correlated with disease severity.

CONCLUSIONS

The TCRβ repertoire is significantly altered in SLE, with potential implications for diagnostics and therapeutics. The identified hub genes may serve as novel biomarkers for SLE, and the findings contribute to the understanding of the immunopathogenesis of the disease.

Serum dsDNA is environmentally contingent

Psoriasis is a recurrent autoimmune disease characterized by seasonal and latitudinal variations. Double-stranded DNA (dsDNA) is a crucial component of nucleic acids and nucleosomes that provoke innate immune responses. Given the potential influence of climate on immunity and the development of autoimmune diseases, a comprehensive quantitative analysis of dsDNA levels in the population is warranted. In this case-control study conducted from 2016 to 2020, 10,110 psoriasis patients and matched controls from 12 regions in China were included. This study examined variations in serum dsDNA levels based on season and latitude. The results revealed significant associations between geographical location, climatic conditions, and season with serum dsDNA concentration. Individuals residing in Northern China exhibited significantly higher serum dsDNA levels compared to those in the South (1.00 vs. 0.96 ng/ml), and those in medium latitude regions had higher levels than their counterparts in areas with extreme latitudes (0.98 vs. 0.96 ng/ml). Furthermore, individuals in regions with low to medium ultraviolet exposure demonstrated higher serum dsDNA concentrations than those in areas with high ultraviolet levels (1.03 vs. 0.93 ng/ml), and individuals in winter showed higher levels than those in summer (1.03 vs. 0.92 ng/ml). Factors such as sex, UV index, humidity, and sunshine duration were inversely related to serum dsDNA levels, while age and daylight hours showed a positive association. These findings suggest that meteorological and climatic factors play a role in influencing serum dsDNA levels.

Phenotypes of patients with lupus-associated pulmonary hypertension in the Chinese Han population: a cluster analysis

OBJECTIVE

Pulmonary hypertension (PH) is a severe complication of systemic lupus erythematosus (SLE). This study investigated the clinical features of patients with SLE-PH in China based on disease manifestations and organ involvement to define precise treatment of SLE and early prevention of complications.

METHODS

In total, 205 SLE-PH patients were included in this study. A cluster analysis was applied according to six clinical and serological variables to define different subgroups of patients. The survival rates of SLE-PH patients and risk factors that influenced prognosis were also compared and a clinical prediction model was developed for the diagnosis of associated lupus nephritis (LN).

RESULTS

Patients were clustered in five groups. Patients in cluster 1 had severe renal damage (all patients had LN and had the highest creatinine and urea nitrogen and the lowest eGFR levels). Patients in cluster 2 had mild renal damage (more than half of the patients had associated LN and 87.5% had increased urinary protein levels but presented a lower degree of renal damage than those in the first group. Patients in cluster 3 had low-grade proteinuria (all patients had 24h urinary protein < 0.5g). Patients in cluster 4 had hematuria or urinary tubular damage (26% of patients had associated LN, but none of the patients had proteinuria. In cluster 5, patients barely had any major organ involvement. The clinical prediction model for a diagnosis of SLE-PH-LN was anti-dsDNA antibodies > 364.64 IU/mL and neutrophil-to-leukocyte ratio (NLR) > 5.55.

CONCLUSION

Our findings provide evidence indicating that SLE-PH presents varying clinical phenotypes and the treatment varies accordingly, suggesting the need for individualized treatment. Key Points • Clustered grouping of patients with SLE-PH is associated with renal injury. • This may be because PH and LN share a common pathogenesis. • The clinical prediction model for a diagnosis of SLE-PH-LN was anti-dsDNA antibodies >364.64 IU/mL and NLR >5.55.

The effects of curcumin supplementation on inflammatory markers in systemic lupus erythematosus patients: a randomized placebo-controlled trial

PURPOSE

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with multisystem involvement. This study was designed to examine the effects of curcumin, a polyphenolic compound isolated from turmeric rhizomes, on inflammatory markers in SLE patients.

METHODS

Seventy 18-60 years old SLE patients were recruited in this randomized triple-blinded placebo-controlled trial, and 62 completed the study. Curcumin group received 1000 mg curcumin daily and the placebo group received placebo capsules for 10 weeks. Dietary intakes and serum levels of complement C3 and C4, complement hemolytic 50%, rheumatoid factor, anti-double stranded DNA (anti-ds DNA), erythrocyte sedimentation rate, high-sensitivity C-reactive protein, interlukine-6 (IL-6) and tumor necrosis factor-α were assessed before and after intervention period.

RESULTS

Curcumin supplementation caused a significant reduction in anti-ds DNA and IL-6 levels at the end of the trial in comparison with baseline (52.57 ± 40.21 vs. 43.27 ± 28.34, p = 0.014 and 127.11 ± 76.63 vs. 101.49 ± 59.08, p = 0.002, respectively). Analysis of covariance which was adjusted for confounding variables also revealed that anti-ds DNA and IL-6 levels decreased significantly in curcumin group compared to placebo group by the end of the intervention period (change:-9.30 ± 19.59 vs. -2.55 ± 17.55, p = 0.018 and - 25.62 ± 42.33 vs. -7.34 ± 34.32, p = 0.043, respectively). No significant changes were observed in levels of other variables during the study (p > 0.05).

CONCLUSION

Curcumin as an effective and safe adjuvant therapy, ameliorated the autoimmune activity and inflammation in SLE patients via reducing anti-ds DNA and IL-6 levels.

CLINICAL TRIAL REGISTRATION

irct.behdasht.gov.ir, identifier: IRCT20210425051077N1.

Evaluation of ocular surface inflammation and systemic conditions in patients with systemic lupus erythematosus: a cross-sectional study

OBJECTIVE

The cross-sectional study was designed to evaluate the association of ocular surface inflammation with systemic conditions in patients with systemic lupus erythematosus (SLE).

METHODS

The study enrolled 30 SLE patients and 30 controls. Ocular symptoms were evaluated using the Ocular Surface Disease Index (OSDI) questionnaire. Tear samples from all participants were collected for tear multi-cytokine and chemokine concentration analysis. All participants were assessed for dry eye disease (DED), including Schirmer I test, tear break-up time (TBUT), corneal fluorescein staining (CFS), meibomian gland secretion (MGS), lid-parallel conjunctival folds (LIPCOF), corneal clarity, and symblepharon. Besides, all participants were also examined for conjunctival impression cytology to measure the density of conjunctival goblet cells (CGCs). The peripheral blood indicators from SLE patients were also collected to measure the SLE-associated autoantibody specificities and systemic inflammatory indicators. Pearson and Spearman's analysis were uesd to examine the correlation between tear cytokines, CGCs, DED-related indicators, and systemic conditions.

RESULTS

The two groups were matched for age and gender in this study. 36.67% of eyes (11 in 30) of SLE patients and 13.33% of eyes (4 in 30) of controls were diagnosed with DED. OSDI scores, abnormal TBUT percentages, CFS percentages, and DED grading were all higher in SLE patients than in control group, while density of CGCs was lower. There were no significant differences in Schirmer I test, MGS, LIPCOF, corneal clarity, and symblepharon between SLE patients and controls. The levels of tear chemokine (C-X-C motif) ligand 11 (CXCL11) and cytokine interleukin-7 (IL-7) in patients with SLE were significantly higher than those in control group. Moreover, among SLE patients, the severity of DED and the level of tear chemokine CXCL11 were significantly positively correlated with SLE-associated autoantibody specificities.

CONCLUSION

Dry eye and tear cytokines and chemokines-mediated ocular surface inflammation persist in SLE patients and are associated with systemic conditions. Therefore, it is necessary for patients with SLE to combine systemic and ocular assessments.

Genome-wide characterization of extrachromosomal circular DNA in SLE and functional analysis reveal their association with apoptosis

Extrachromosomal circular DNA (eccDNA) derived from linear chromosomes, are showed typical nucleosomal ladder pattern in agarose gel which as a known feature of apoptosis and demonstrated to be immunogenicity. In systemic lupus erythematosus (SLE) patients, elevated levels of cell-free DNA (cfDNA) can be found in either linear forms or circular forms, while circular ones are much less common and harder to detect. The molecular characteristics and function of circular forms in plasma SLE patients remains elusive. Herein, we characterized the hallmarks of plasma eccDNA in SLE patients, including the lower normalized number and GC content of eccDNA in SLE plasma than in the healthy, and SLE eccDNA number positively correlated with C3 and negatively with anti-dsDNA antibodies. The differential eccGenes (eccDNAs carrying the protein coding gene sequence) of SLE was significantly enriched in apoptosis-related pathways. The artificially synthesized eccDNA with sequences of the PRF1 exon region could promote transcriptional expression of PRF1, IFNA and IFIT3 and inhibit early-stage apoptosis. Plasma eccDNA can serve as a novel autoantigen in the pathogenesis of SLE.

Lupus and other autoimmune diseases: Epidemiology in the population of African ancestry and diagnostic and management challenges in Africa

Autoimmune diseases are prevalent among people of African ancestry living outside Africa. However, the burden of autoimmune diseases in Africa is not well understood. This article provides a global overview of the current burden of autoimmune diseases in individuals of African descent. It also discusses the major factors contributing to autoimmune diseases in this population group, as well as the challenges involved in diagnosing and managing autoimmune diseases in Africa.

Activation of circulating TFH17 cells associated with activated naive and double negative 2 B cell expansion, and disease activity in systemic lupus erythematosus patients

BACKGROUND

Systemic lupus erythematosus (SLE) is the quintessential autoimmune disease, as it is characterized by hyperactivity of CD4+ T cells and subsequently drives lupus pathology. Follicular helper T (TFH) cells play an important role in B cell maturation and antibody production. However, which specific subset of cTFH cells drives B cell function and contributes to the development of anti-dsDNA antibodies and SLE pathogenesis remains unclear.

METHODS

Peripheral blood mononuclear cells from SLE patients with inactive (n = 11) and active (n = 21) were used to determine and detect frequencies and phenotypes of circulating TFH cells (cTFH), memory cTFH, and B cell subsets. The correlations among cTFH cell subsets and phenotypes, B cell subsets, anti-dsDNA autoantibodies, and clinical parameters were analyzed.

RESULTS

In subjects with active SLE, cTFH1 and cTFH17 cells were significantly expanded and activated. These expanded cTFH cells expressed memory phenotypes; cTFH1 cells were predominantly central memory (CM) type, while cTFH17 cells were largely effector memory (EM) type. Phenotyping B cell subsets in these patients showed increased frequencies of aNAV and DN2 B cells. Clinically, ICOS+ cTFH1, ICOS+ cTFH17 cells, and SLEDAI-2k scores were found to be correlated. Analysis of cTFH-B cell relationship revealed positive correlations among ICOS+ cTFH1 cells, aNAV B cells, and anti-dsDNA antibodies. Activation of ICOS+ cTFH17 cells was significantly related to the expansion of aNAV and DN2 B cells. The presence of CM cells in cTFH1 and cTFH17 subsets was correlated with aNAV and DN2 B cell frequencies.

CONCLUSION

SLE cTFH cells were found to be polarized toward cTFH1 and cTFH17 cells; activation of these cTFH subsets was significantly associated with disease activity score, aNAV, DN2 B cell expansion, and anti-dsDNA antibody level. Thus, the interactions among cTFH1, cTFH17, and B cells likely contribute to the development of autoantibodies and the pathogenesis in SLE.

Mycophenolate Mofetil and New-Onset Systemic Lupus Erythematosus: A Randomized Clinical Trial

Importance

Anti-double-stranded DNA (dsDNA) antibody has been reported to have a close relationship with systemic lupus erythematosus (SLE) flares and participates in the pathogenesis of lupus nephritis (LN) as well as causing damage to other organs. However, whether early use of mycophenolate mofetil (MMF) could prevent SLE flares is not clear.

Objective

To assess the efficacy and safety of MMF plus prednisone and hydroxychloroquine sulfate compared with prednisone and hydroxychloroquine sulfate alone in patients with SLE.

Design, Setting, and Participants

This investigator-initiated, multicenter, observer-blinded randomized clinical trial enrolled 130 participants aged 18 to 65 years and was conducted in 3 hospitals across China. Treatment-naive patients with newly diagnosed SLE, a high titer of anti-dsDNA antibody, and no major organ involvement were included. The study was started September 1, 2018, and the follow-up was completed September 30, 2021. Data were analyzed from December 1, 2021, to March 31, 2022.

Interventions

Patients were randomized 1:1 to receive oral prednisone (0.5 mg/kg/d) and hydroxychloroquine sulfate (5 mg/kg/d) (control group) or prednisone (0.5 mg/kg/d) and hydroxychloroquine sulfate (5 mg/kg/d) plus MMF (500 mg twice daily) (MMF group) for 96 weeks.

Main Outcomes and Measures

The primary outcome was the proportion of patients presenting with flares according to the Safety of Estrogens in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) Flare Index. The secondary outcomes included the proportion with lupus low disease activity state at week 96, 36-Item Short Form Health Survey scores before and after treatment, proportion of adverse events (AEs), and changes in SLEDAI-2000 scores and prednisone doses.

Results

Among 130 randomized patients (mean [SD] age, 34.5 [12.5] years; 112 [86.2%] women), 119 (91.5%) completed the follow-up. The risk of severe flare was significantly lower in the MMF group (7 of 65 [10.8%]) vs the control group (18 of 65 [27.7%]) (relative risk [RR], 0.39 [95% CI, 0.17-0.87]; P = .01). Additionally, 1 of 65 patients in the MMF group (1.5%) and 9 of 65 in the control group (13.8%) manifested LN (RR, 0.11 [95% CI, 0.01-0.85]; P = .008). Most common serious study drug-related AEs were infections (20 of 65 [30.8%] in the control group and 22 of 65 [33.8%] in the MMF group).

Conclusions and Relevance

The findings of this randomized clinical trial suggest that MMF may reduce the rate of severe flare and lower the incidence of LN in patients with new-onset SLE and a high titer of anti-dsDNA antibody without major organ involvement.

Trial Registration

Chinese Clinical Trial Registry: ChiCTR1800017540.

Glycosylation: mechanisms, biological functions and clinical implications

Protein post-translational modification (PTM) is a covalent process that occurs in proteins during or after translation through the addition or removal of one or more functional groups, and has a profound effect on protein function. Glycosylation is one of the most common PTMs, in which polysaccharides are transferred to specific amino acid residues in proteins by glycosyltransferases. A growing body of evidence suggests that glycosylation is essential for the unfolding of various functional activities in organisms, such as playing a key role in the regulation of protein function, cell adhesion and immune escape. Aberrant glycosylation is also closely associated with the development of various diseases. Abnormal glycosylation patterns are closely linked to the emergence of various health conditions, including cancer, inflammation, autoimmune disorders, and several other diseases. However, the underlying composition and structure of the glycosylated residues have not been determined. It is imperative to fully understand the internal structure and differential expression of glycosylation, and to incorporate advanced detection technologies to keep the knowledge advancing. Investigations on the clinical applications of glycosylation focused on sensitive and promising biomarkers, development of more effective small molecule targeted drugs and emerging vaccines. These studies provide a new area for novel therapeutic strategies based on glycosylation.

Baricitinib in the treatment of systemic lupus erythematosus: a systematic review of randomized controlled trials

BACKGROUND

Baricitinib, a Janus Kinase (JAK) inhibitor, has emerged as a potential therapeutic option for systemic lupus erythematosus (SLE). This systematic review aims to synthesize evidence from randomized controlled trials (RCTs) evaluating the potential of baricitinib in treating SLE.

METHODS

A systematic search was conducted across electronic databases to identify relevant RCTs assessing baricitinib in patients with SLE. Studies reporting outcomes such as the Systemic Lupus Erythematosus Responder Index-4 (SRI-4), adverse events, and safety profiles were included. Data extraction and quality assessment were performed following PRISMA guidelines.

RESULTS

A total of four studies were evaluated for efficacy and safety of baricitinib therapy. Three studies reported SRI-4, British Isles Lupus Assessment Group (BILAG), and Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI-2K), except for Dorner and colleagues Only Dorner and colleagues and Wallace and colleagues discuss the anti-dsDNA titres following treatment with baricitinib. The findings consistently demonstrated improved efficacy of baricitinib compared to placebo, particularly in terms of SRI-4 scores. Higher dosages of baricitinib showed significant improvement in disease activity and severity indices. Adverse events, including infections and gastrointestinal disturbances, were reported.

CONCLUSION

Baricitinib holds promise for treating SLE, but caution is needed due to potential adverse events. Careful patient selection and monitoring are crucial. Future research should prioritize long-term safety and comparative effectiveness studies to better understand baricitinib's role in managing SLE.

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.

Fat-associated lymphoid clusters: Supporting visceral adipose tissue B cell function in immunity and metabolism

It is now widely understood that visceral adipose tissue (VAT) is a highly active and dynamic organ, with many functions beyond lipid accumulation and storage. In this review, we discuss the immunological role of this tissue, underpinned by the presence of fat-associated lymphoid clusters (FALCs). FALC's distinctive structure and stromal cell composition support a very different immune cell mix to that found in classical secondary lymphoid organs, which underlies their unique functions of filtration, surveillance, innate-like immune responses, and adaptive immunity within the serous cavities. FALCs are important B cell hubs providing B1 cell-mediated frontline protection against infection and supporting B2 cell-adaptative immune responses. Beyond these beneficial immune responses orchestrated by FALCs, immune cells within VAT play important homeostatic role. Dysregulation of immune cells during obesity and aging leads to chronic pathological "metabolic inflammation", which contributes to the development of cardiometabolic diseases. Here, we examine the emerging and complex functions of B cells in VAT homeostasis and the metabolic complications of obesity, highlighting the potential role that FALCs play and emphasize the areas where further research is needed.

Combining Anti-Mitochondrial Antibodies, Anti-Histone, and PLA2/COX Biomarkers to Increase Their Diagnostic Accuracy for Autism Spectrum Disorders

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairments in social interaction and restricted and repetitive behaviors. Oxidative stress may be a critical link between mitochondrial dysfunction and ASD as reactive oxygen species (ROS) generated from pro-oxidant environmental toxicants and activated immune cells can result in mitochondrial failure. Recently, mitochondrial dysfunction, autoimmunity, and abnormal lipid mediators have been identified in multiple investigations as an acknowledged etiological mechanism of ASD that can be targeted for therapeutic intervention.

METHODS

The relationship between lipid mediator markers linked to inflammation induction, such as phospholipase A2/cyclooxygenase-2 (PLA2/Cox-2), and the mitochondrial dysfunction marker anti-mitochondrial antibodies (AMA-M2), and anti-histone autoantibodies in the etiology of ASD was investigated in this study using combined receiver operating characteristic (ROC) curve analyses. This study also sought to identify the linear combination for a given set of markers that optimizes the partial area under ROC curves. This study included 40 age- and sex-matched controls and 40 ASD youngsters. The plasma of both groups was tested for PLA2/COX-2, AMA-M2, and anti-histone autoantibodies' levels using ELISA kits. ROC curves and logistic regression models were used in the statistical analysis.

RESULTS

Using the integrated ROC curve analysis, a notable rise in the area under the curve was noticed. Additionally, the combined markers had markedly improved specificity and sensitivity.

CONCLUSIONS

The current study suggested that measuring the predictive value of selected biomarkers related to mitochondrial dysfunction, autoimmunity, and lipid metabolism in children with ASD using a ROC curve analysis could lead to a better understanding of the etiological mechanism of ASD as well as its relationship with metabolism.

SLE: a cognitive step forward-a synthesis of rethinking theories, causality, and ignored DNA structures

Systemic lupus erythematosus (SLE) is classified by instinctual classification criteria. A valid proclamation is that these formally accepted SLE classification criteria legitimate the syndrome as being difficult to explain and therefore enigmatic. SLE involves scientific problems linked to etiological factors and criteria. Our insufficient understanding of the clinical condition uniformly denoted SLE depends on the still open question of whether SLE is, according to classification criteria, a well-defined one disease entity or represents a variety of overlapping indistinct syndromes. Without rational hypotheses, these problems harm clear definition(s) of the syndrome. Why SLE is not anchored in logic, consequent, downstream interdependent and interactive inflammatory networks may rely on ignored predictive causality principles. Authoritative classification criteria do not reflect consequent causality criteria and do not unify characterization principles such as diagnostic criteria. We need now to reconcile legendary scientific achievements to concretize the delimitation of what SLE really is. Not all classified SLE syndromes are "genuine SLE"; many are theoretically "SLE-like non-SLE" syndromes. In this study, progressive theories imply imperative challenges to reconsider the fundamental impact of "the causality principle". This may offer us logic classification and diagnostic criteria aimed at identifying concise SLE syndromes as research objects. Can a systems science approach solve this problem?

RNA-DNA triplexes: molecular mechanisms and functional relevance

Interactions of RNA with DNA are principles of gene expression control that have recently gained considerable attention. Among RNA-DNA interactions are R-loops and RNA-DNA hybrid G-quadruplexes, as well as RNA-DNA triplexes. It is proposed that RNA-DNA triplexes guide RNA-associated regulatory proteins to specific genomic locations, influencing transcription and epigenetic decision making. Although triplex formation initially was considered solely an in vitro event, recent progress in computational, biochemical, and biophysical methods support in vivo functionality with relevance for gene expression control. Here, we review the central methodology and biology of triplexes, outline paradigms required for triplex function, and provide examples of physiologically important triplex-forming long non-coding RNAs.

Association of Systemic Markers of Inflammation with Signs and Symptoms of Dry Eye Disease and Sjogren's Syndrome in the Dry Eye Assessment and Management (DREAM©) Study

PURPOSE

To evaluate the possible role of systemic inflammation in dry eye disease (DED) via systemic inflammatory marker associations with DED signs and symptoms, and an analysis of a subgroup with Sjogren's Syndrome (SS).

METHODS

Participant serums were analyzed using line immunoassays (LIAs) for the presence of antibodies against 34 systemic inflammatory markers. Using the 2012 American College of Rheumatology definition, the 481 participants were categorized into group 1 (SS; n = 52), group 2 (autoimmune disease not including SS; n = 66), or group 3 (control, i.e. no autoimmune disease; n = 363).

RESULTS

3 markers were positive in ≥10% of participants: Ro52 (19.3%), Scl-70 (15.0%), CN-1A (14.2%). 2 markers were positively associated with symptoms: PM-Scl100 (p = 0.02), Sm (p = 0.009). 5 markers were positively associated with signs: U2SnRNP A', Ro52, La, DNA, Ro60. SS participants showed significantly higher positivity for 4 markers compared to participants with no autoimmune disease: PL-7 (p = 0.02), Ro52 (p < 0.0001), La (p < 0.0001), Ro60 (p < 0.0001). SS participants showed significantly higher positivity for 3 markers compared to participants with another autoimmune disease: Ro52 (p < 0.0001), La (p = 0.002), Ro60 (p < 0.0001).

CONCLUSIONS

This study did not show evidence of significant systemic inflammation in participants with moderate-to-severe DED, based on the markers tested. PM-Scl100 and Sm may be associated with more severe DED symptoms. U2SnRNP A', Ro52, La, DNA, and Ro60 may be associated with more severe ocular surface disease. Ro52 and PL-7 may be diagnostic markers for SS. Future research evaluating these relationships and their clinical significance is needed.

High-throughput assays to assess variant effects on disease

Interpreting the wealth of rare genetic variants discovered in population-scale sequencing efforts and deciphering their associations with human health and disease present a critical challenge due to the lack of sufficient clinical case reports. One promising avenue to overcome this problem is deep mutational scanning (DMS), a method of introducing and evaluating large-scale genetic variants in model cell lines. DMS allows unbiased investigation of variants, including those that are not found in clinical reports, thus improving rare disease diagnostics. Currently, the main obstacle limiting the full potential of DMS is the availability of functional assays that are specific to disease mechanisms. Thus, we explore high-throughput functional methodologies suitable to examine broad disease mechanisms. We specifically focus on methods that do not require robotics or automation but instead use well-designed molecular tools to transform biological mechanisms into easily detectable signals, such as cell survival rate, fluorescence or drug resistance. Here, we aim to bridge the gap between disease-relevant assays and their integration into the DMS framework.

Natural Antibodies Produced in Vaccinated Patients and COVID-19 Convalescents Hydrolyze Recombinant RBD and Nucleocapsid (N) Proteins

Antibodies are protein molecules whose primary function is to recognize antigens. However, recent studies have demonstrated their ability to hydrolyze specific substrates, such as proteins, oligopeptides, and nucleic acids. In 2023, two separate teams of researchers demonstrated the proteolytic activity of natural plasma antibodies from COVID-19 convalescents. These antibodies were found to hydrolyze the S-protein and corresponding oligopeptides. Our study shows that for antibodies with affinity to recombinant structural proteins of the SARS-CoV-2: S-protein, its fragment RBD and N-protein can only hydrolyze the corresponding protein substrates and are not cross-reactive. By using strict criteria, we have confirmed that this proteolytic activity is an intrinsic property of antibodies and is not caused by impurities co-eluting with them. This discovery suggests that natural proteolytic antibodies that hydrolyze proteins of the SARS-CoV-2 virus may have a positive impact on disease pathogenesis. It is also possible for these antibodies to work in combination with other antibodies that bind specific epitopes to enhance the process of virus neutralization.

A Conditionally Activated Cytosol-Penetrating Antibody for TME-Dependent Intracellular Cargo Delivery

Currently, therapeutic and diagnostic applications of antibodies are primarily limited to cell surface-exposed and extracellular proteins. However, research has been conducted on cell-penetrating peptides (CPP), as well as cytosol-penetrating antibodies, to overcome these limitations. In this context, a heparin sulfate proteoglycan (HSPG)-binding antibody was serendipitously discovered, which eventually localizes to the cytosol of target cells. Functional characterization revealed that the tested antibody has beneficial cytosol-penetrating capabilities and can deliver cargo proteins (up to 70 kDa) to the cytosol. To achieve tumor-specific cell targeting and cargo delivery through conditional activation of the cell-penetrating antibody in the tumor microenvironment, a single-chain Fc fragment (scFv) and a VL domain were isolated as masking units. Several in vitro assays demonstrated that fusing the masking protein with a cleavable linker to the cell penetration antibody results in the inactivation of antibody cell binding and internalization. Removal of the mask via MMP-9 protease cleavage, a protease that is frequently overexpressed in the tumor microenvironment (TME), led to complete regeneration of binding and cytosol-penetrating capabilities. Masked and conditionally activated cytosol-penetrating antibodies have the potential to serve as a modular platform for delivering protein cargoes addressing intracellular targets in tumor cells.

Anti-DNA antibody-targeted D-peptide nanoparticles ameliorate lupus nephritis in MRL/lpr mice

Peptide ALW (ALWPPNLHAWVP) targeting anti-dsDNA antibodies has shown promising therapeutic effects in alleviating lupus nephritis, but is potentially limited by poor stability and non-kidney targeting. We recently developed a D-form modified ALW, called D-ALW, which has the capacity to widely inhibit pathogenic polyclonal anti-dsDNA antibody reactions. Further modification of D-ALW using PEG-PLGA nanoparticles to enhance good kidney-targeting ability and extend half-life. Here, we demonstrate that the D-form modified ALW maintains higher binding and inhibition efficiencies and achieves higher stability. Most importantly, D-ALW nanoparticles exhibit excellent kidney-targeting ability and prolong the half-life of the peptides in BALB/c mice. Additionally, compared to D-ALW, D-ALW nanoparticles significantly reduce the glomerular deposition of IgG and C3, improve renal histopathologies, such as glomerular proliferation and inflammatory cells infiltration, and markedly prolong lifespan in MRL/lpr lupus-prone mice. Overall, these results establish that the D-ALW nanoparticles offer synergistic benefits in both safety and efficacy, providing long-term renal preservation and treatment advantages in lupus nephritis.

Significant heightened methylation levels of RUNX3 gene promoter in patients with systemic lupus erythematosus

OBJECTIVE

Researchers are actively investigating new diagnostic and prognostic biomarkers that offer improved sensitivity and specificity for systemic lupus erythematosus (SLE). One area of interest is DNA methylation changes. Previous studies have shown a connection between the RUNX3 gene dysfunction and SLE. In this study, the focus was on examining the methylation level of the RUNX3 promoter in peripheral blood mononuclear cells (PBMCs) of SLE patients and healthy individuals.

METHODS

A total of 80 individuals diagnosed with SLE from Iran, along with 77 healthy individuals, were included. The methylation levels of the RUNX3 gene in the extracted DNA were evaluated using the MethyQESD method. To determine the diagnostic effectiveness of the RUNX3 promoter methylation level, a receiver operating characteristic (ROC) curve was generated.

RESULTS

The methylation of the RUNX3 promoter was found to be significantly higher in patients with SLE compared to healthy individuals (p < .001). This difference in methylation levels was observed between SLE patients and healthy individuals and between SLE patients with renal involvement and those without renal involvement (86.29 ± 10.30 vs 40.28 ± 24.21, p < .001). ROC analyses revealed that the methylation level of the RUNX3 promoter had a diagnostic power of 0.769 [95% CI (0.681-0.814)] for SLE. Additionally, there was a positive correlation between the RUNX3 methylation level and levels of creatinine and C4.

CONCLUSION

The findings of this study emphasize the potential use of RUNX3 methylation levels in PBMCs of SLE patients as biomarkers for diagnosing the disease, predicting renal damage, and assessing disease activity.

Precise Targeting of Autoantigen-Specific B Cells in Lupus Nephritis with Chimeric Autoantibody Receptor T Cells

Despite conventional therapy, lupus nephritis (LN) remains a significant contributor to short- and long-term morbidity and mortality. B cell abnormalities and the production of autoantibodies against nuclear complexes like anti-dsDNA are recognised as key players in the pathogenesis of LN. To address the challenges of chronic immunosuppression associated with current therapies, we have engineered T cells to express chimeric autoantibody receptors (DNA-CAART) for the precise targeting of B cells expressing anti-dsDNA autoantibodies. T cells from LN patients were transduced using six different CAAR vectors based on their antigen specificity, including alpha-actinin, histone-1, heparan sulphate, or C1q. The cytotoxicity, cytokine production, and cell-cell contact of DNA-CAART were thoroughly investigated in co-culture experiments with B cells isolated from patients, both with and without anti-dsDNA positivity. The therapeutic effects were further evaluated using an in vitro immune kidney LN organoid. Among the six proposed DNA-CAART, DNA4 and DNA6 demonstrated superior selectively cytotoxic activity against anti-dsDNA+ B cells. Notably, DNA4-CAART exhibited improvements in organoid morphology, apoptosis, and the inflammatory process in the presence of IFNα-stimulated anti-dsDNA+ B cells. Based on these findings, DNA4-CAART emerge as promising candidates for modulating autoimmunity and represent a novel approach for the treatment of LN.

Using combination of albumin to fibrinogen ratio and prognostic nutritional index model for predicting disease activity in patients with systemic lupus erythematosus

Background: Systemic lupus erythematosus (SLE) is chronic autoimmune disease with multiple organ damage and is associated with poor prognosis and high mortality. Identification of universal biomarkers to predict SLE activity is challenging due to the heterogeneity of the disease. This study aimed to identify the indicators that are sensitive and specific to predict activity of SLE.Methods: We retrospectively analyzed 108 patients with SLE. Patients were categorized into SLE with activity and without activity groups on the basis of SLE disease activity index. We analyzed the potential of routine and novel indicators in predicting the SLE activity using receiver operating characteristic curves and multivariate logistic regression. The Spearman method was used to understand the correlation between albumin to fibrinogen ratio (AFR), prognostic nutritional index (PNI), AFR-PNI model and disease activity.Results: SLE with activity group had higher ESR, CRP, D-dimer, fibrinogen, CRP to albumin ratio, positive rate of anti-dsDNA and ANUA, and lower C3, total bilirubin, total protein, albumin, albumin/globulin, creatinine, high density liptein cholesterol, hemoglobin, hematocrit, lymphocyte count, positive rate of anti-SSA, AFR, PNI than SLE without activity. A further established model based on combination of AFR and PNI (AFR-PNI model) showed prominent value in distinguishing SLE with activity patients from SLE without activity patients. In addition, the sensitivity and specificity of AFR-PNI model + anti-dsDNA combination model were superior to AFR-PNI model. AFR and PNI were risk factors for SLE activity. Moreover, AFR+PNI model correlated with disease activity and AFR-PNI model was associated with fever, pleurisy, pericarditis, renal involvement.Conclusion: These findings suggest that predictive model based on combination of AFR and PNI may be useful markers to identify active SLE in clinical practice.

Exploring the Molecular Mechanisms and Shared Gene Signatures Between Systemic Lupus Erythematosus and Bladder Urothelial Carcinoma

Background

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease associated with increased susceptibility to cancer, including bladder urothelial carcinoma (BLCA). This study investigates the shared molecular mechanisms and gene signatures between SLE and BLCA, shedding light on potential biomarkers and therapeutic targets.

Methods

We compiled gene datasets related to SLE and BLCA from various databases and identified common genes. Differential gene expression analysis, protein-protein interaction networks, and hub gene identification were performed. We studied functional enrichment, immune infiltration, and transcription factor/miRNA regulation networks. We also explored gene-disease interactions and protein-chemical/drug networks. Hub gene expression levels and diagnostic values were validated in TCGA and GEO databases. Prognostic analysis was performed on the core gene MMP9 in the TCGA-BLCA database to study its prognostic value. Finally, the mRNA expression of MMP9 was verified in bladder cancer cell lines and BLCA patient blood. The diagnostic value of MMP9 for BLCA was verified by receiver operating characteristic(ROC) curve analysis of the expression of MMP9 in patients' blood.

Results

We identified 524 common genes between SLE and BLCA, enriched in pathways related to apoptosis and cytokine regulation. Immune infiltration analysis for two diseases. Transcription factors and microRNAs were implicated in regulating these common genes. The gene-disease network linked hub genes with various diseases, emphasizing their roles in autoimmune disease and cancer. Protein-chemical/drug networks highlighted potential treatment options. Finally, our study found that MMP9 is a potential therapeutic target with diagnostic and prognostic value and Immune-related biomarkers in patients with BLCA and SLE.

Conclusion

Our study reveals shared molecular mechanisms, genetic signatures, and immune infiltrates between SLE and BLCA. MMP9 emerges as a potential diagnostic and prognostic biomarker in BLCA, warranting further investigation. These findings provide insights into the pathogenesis of SLE-associated BLCA and may guide future research and therapeutic strategies.

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

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

Anti-Toxoplasma gondii antibodies as a risk factor for the prevalence and severity of systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is a complex systemic autoimmune disease characterized by the presence of numerous autoantibodies. The interaction of infectious agents (viruses, bacteria and parasites) and a genetically susceptible host may be a key mechanism for SLE. Toxoplasma gondii is a widespread intracellular parasite that has been implicated in the pathogenesis of autoimmune diseases. However, the relationship between T. gondii infection and the increased risk of SLE in Chinese populations remains unclear.

METHODS

The seroprevalence of T. gondii infection was assessed in 1771 serum samples collected from Chinese individuals (908 healthy controls and 863 SLE patients) from different regions of China using an enzyme-linked immunosorbent assay. Serum autoantibodies and clinical information were obtained and analysed.

RESULTS

Our observations revealed a higher prevalence of anti-T. gondii antibodies (ATxA) immunoglobulin G (IgG) in serum samples from SLE patients (144/863, 16.7%) than in those from the healthy controls (53/917, 5.8%; P < 0.0001), indicating a 2.48-fold increased risk of SLE in the ATxA-IgG+ population, after adjustment for age and sex (95% confidence interval [CI] 1.70-3.62, P < 0.0001). ATxA-IgG+ SLE patients also showed a 1.75-fold higher risk of developing moderate and severe lupus symptoms (95% CI 1.14-2.70, P = 0.011) compared to ATxA-IgG- patients. Relative to ATxA-IgG- patients, ATxA-IgG+ patients were more likely to develop specific clinical symptoms, including discoid rash, oral ulcer, myalgia and alopecia. Seven antibodies, namely anti-ribosomal RNA protein (rRNP), anti-double stranded DNA (dsDNA), anti-cell membrane DNA (cmDNA), anti-scleroderma-70 (Scl-70), anti-cardiolipin (CL), anti-beta2-glycoprotein-I (B2GPI) and rheumatoid factor (RF), occurred more frequently in ATxA-IgG+ patients. When combined with anti-dsDNA and RF/anti-rRNP/anti-cmDNA/ESR, ATxA-IgG significantly increased the risk for severe lupus.

CONCLUSIONS

Our results suggest that ATxA-IgG may be a significant risk factor for SLE prevalence and severity in Chinese populations.

Neuropeptide Y, a potential marker for lupus, promotes lupus development

OBJECTIVE

Relationship between neuropeptide Y (NPY) serum levels, NPY genetic mutation with systemic lupus erythematosus (SLE) pathogenesis is yet to be clarified, and role of NPY in development of SLE needs elucidation.

METHOD

This study included 460 SLE patients, 472 non-SLE cases, 500 healthy volunteers. Serum NPY, matrix metalloproteinase-1 (MMP-1) and MMP-8 levels were tested by ELISA. Genotyping 7 NPY single nucleotides polymorphisms (SNPs) (rs5573, rs5574, rs16129, rs16138, rs16140, rs16147, rs16478) was obtained by Kompetitive Allele-Specific PCR (KASP) method. Pristane-induced lupus mice were treated with NPY-Y1 receptor antagonist, and histological analysis, serological changes of the mice were evaluated.

RESULTS

NPY serum concentrations were significantly increased in SLE patients when compared to that in healthy volunteers, non-SLE cases. Rs5573 G allele, rs16129 T allele, rs16147 G allele frequencies were significantly different between SLE cases and healthy controls. Rs5574 TT + TC genotypes were related to levels of IgG, C3, C4 and erythrocyte sedimentation rate, and rs16138 GG + GC genotypes correlated with SLE cases with anti-double-stranded deoxyribonucleic acid antibody (anti-dsDNA) (+). Serum MMP-1, MMP-8 concentrations were higher in SLE patients, and NPY levels were significantly related to MMP-1, MMP-8 levels. After treatment of lupus mice with NPY-Y1 receptor antagonist, damage of liver, spleen and kidney was alleviated, production of autoantibodies (anti-nuclear antibody (ANA), total IgG, anti-dsDNA) and MMP-1, MMP-8 was down-regulated, and differentiation of CD3+, CD8+ T cells, B cells, monocytes, macrophages, T helper 1 (Th1), Th2, Th17 cells was reversed.

CONCLUSION

NPY may be a biomarker for lupus, which may promote occurrence and development of lupus.

ω-3 polyunsaturated fatty acid alleviates systemic lupus erythematosus by suppressing autoimmunity in a murine model

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune inflammatory disease that damages multiple organs by the production of autoantibodies. Numerous research studies have demonstrated the anti-inflammatory effects of ω-3 polyunsaturated fatty acids (PUFAs). A diet rich in ω-3 PUFAs reduces chronic inflammatory and autoimmune conditions. Herein, we investigated the protective effect of ω-3 PUFAs against autoimmune injury in SLE. In a TMPD-induced mouse model of SLE, supplementation with eicosapentaenoic acid (EPA)-rich (97%) fish oil was found to alleviate systemic autoimmune phenotypes such as ascites, lipogranulomas and serum dsDNA levels. In addition, EPA also significantly improved renal manifestations, reducing proteinuria, glomerulonephritis, and immune complex deposition. Mechanistically, ω-3 PUFAs were shown to modulate the differentiation of B lymphocyte subsets of primary splenic lymphocytes in the spontaneous murine lupus model MRL/MpJ-Faslpr in vitro, specifically that both EPA and DHA suppressed the number of total B cells, B1B2 cells and plasma cells. Concurrently, they were also found to promote the secretion of the anti-inflammatory cytokine IL10, mainly produced by Breg and Treg cells. Thus, nutritional supplementation with ω-3 PUFAs can regulate B cell's differentiation and anti-inflammatory function and strongly prevent autoimmune responses and lupus nephritis. The diets balance between ω-6 and ω-3 PUFAs intake may represent a promising treatment strategy to prevent or delay the onset of SLE.

Anti-contactin 1 Antibody-associated Membranous Nephropathy in Chronic Inflammatory Demyelinating Polyneuropathy with Several Autoantibodies

A 50-year-old man diagnosed with anti-contactin 1 (CNTN1) antibody-associated chronic inflammatory demyelinating polyneuropathy (CIDP) was referred to our department for the evaluation of proteinuria. A kidney biopsy revealed membranous nephropathy (MN). Immunohistochemistry for CNTN1 revealed positive granular staining along the glomerular basement membrane, confirming anti-CNTN1 antibody-associated MN. Immunofluorescence showed a full-house pattern, and several autoantibodies, such as anti-nuclear antibody, anti-double-strand DNA antibody, and anti-cardiolipin antibody, were detected in the patient's serum. Although limited autoantibodies have been investigated in some of the reported cases, a variety of autoantibodies might be produced in anti-CNTN1 antibody-associated CIDP, accompanied by MN.

Hydrolysis of Oligodeoxyribonucleotides on the Microarray Surface and in Solution by Catalytic Anti-DNA Antibodies in Systemic Lupus Erythematosus

Anti-DNA antibodies are known to be classical serological hallmarks of systemic lupus erythematosus (SLE). In addition to high-affinity antibodies, the autoantibody pool also contains natural catalytic anti-DNA antibodies that recognize and hydrolyze DNA. However, the specificity of such antibodies is uncertain. In addition, DNA binding to a surface such as the cell membrane, can also affect its recognition by antibodies. Here, we analyzed the hydrolysis of short oligodeoxyribonucleotides (ODNs) immobilized on the microarray surface and in solution by catalytic anti-DNA antibodies from SLE patients. It has been shown that IgG antibodies from SLE patients hydrolyze ODNs more effectively both in solution and on the surface, compared to IgG from healthy individuals. The data obtained indicate a more efficient hydrolysis of ODNs in solution than immobilized ODNs on the surface. In addition, differences in the specificity of recognition and hydrolysis of certain ODNs by anti-DNA antibodies were revealed, indicating the formation of autoantibodies to specific DNA motifs in SLE. The data obtained expand our understanding of the role of anti-DNA antibodies in SLE. Differences in the recognition and hydrolysis of surface-tethered and dissolved ODNs need to be considered in DNA microarray applications.

Demethylation of CDKN2A in systemic lupus erythematosus and rheumatoid arthritis: a blood biomarker for diagnosis and assessment of disease activity

INTRODUCTION/OBJECTIVES

Considering the phenotypic and serological heterogeneity of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), significant challenges may intervene with the precise diagnosis. In this regard, numerous studies have shown that changes in DNA methylation levels can be used to distinguish between healthy individuals and those with SLE and RA, as well as to predict disease activity and prognosis.

METHODS

In the current study, we evaluated quantitative methylation level of CDKN2A promoter in peripheral blood mononuclear cells (PBMCs) of SLE and RA patients, and healthy controls by methylation-quantification of endonuclease-resistant DNA (MethyQESD), a bisulfite conversion-independent method.

RESULTS

Our findings revealed an excessive hypomethylation of CDKN2A in SLE and RA patients compared to healthy individuals (P < 0.001). Besides, by determining efficient cutoff value, the specificity of CDKN2A for correct diagnosis of healthy subjects was measured to be 77.30% and the sensitivity for SLE and RA diagnosis were 81.33%, and 72%, respectively. Furthermore, CDKN2A methylation level was shown to be positively associated with C3 and C4 levels and negatively associated with anti‑dsDNA concentration (P < 0.001). Moreover, a statistically significant difference in the DNA methylation levels of CDKN2A promoter was identified between SLE cases with age of ≤ 18 and patients with > 18 years of age (P = 0.025).

CONCLUSION

Our findings demonstrated that CDKN2A methylation levels in PBMCs of SLE and RA patients could be used as a promising diagnostic biomarker. The significant association between hypomethylation of CDKN2A promoter and disease activity factors in SLE patients, is suggesting that CDKN2A hypomethylation could be used as an alternative biomarker for assessment of disease activity. Key Points • Several studies have reported increased expression of CDKN2A in SLE and RA suggesting that it may be involved in the pathogenesis of these disorders. • CDKN2A hypomethylation has been implicated in different autoimmune diseases. • Our findings demonstrated that CDKN2A methylation levels in PBMCs of SLE and RA patients could be used as a promising diagnostic and prognostic biomarker.

Vaccines for immune tolerance against autoimmune disease

The high prevalence and rising incidence of autoimmune diseases have become a prominent public health issue. Autoimmune disorders result from the immune system erroneously attacking the body's own healthy cells and tissues, causing persistent inflammation, tissue injury, and impaired organ function. Existing treatments primarily rely on broad immunosuppression, leaving patients vulnerable to infections and necessitating lifelong treatments. To address these unmet needs, an emerging frontier of vaccine development aims to restore immune equilibrium by inducing immune tolerance to autoantigens, offering a potential avenue for a cure rather than mere symptom management. We discuss this burgeoning field of vaccine development against inflammation and autoimmune diseases, with a focus on common autoimmune disorders, including multiple sclerosis, type 1 diabetes, rheumatoid arthritis, inflammatory bowel disease, and systemic lupus erythematosus. Vaccine-based strategies provide a new pathway for the future of autoimmune disease therapeutics, heralding a new era in the battle against inflammation and autoimmunity.

Antigen presentation by B cells enables epitope spreading across an MHC barrier

Circumstantial evidence suggests that B cells may instruct T cells to break tolerance. Here, to test this hypothesis, we used a murine model in which a single B cell clone precipitates an autoreactive response resembling systemic lupus erythematosus (SLE). The initiating clone did not need to enter germinal centers to precipitate epitope spreading. Rather, it localized to extrafollicular splenic bridging channels early in the response. Autoantibody produced by the initiating clone was not sufficient to drive the autoreactive response. Subsequent epitope spreading depended on antigen presentation and was compartmentalized by major histocompatibility complex (MHC). B cells carrying two MHC haplotypes could bridge the MHC barrier between B cells that did not share MHC. Thus, B cells directly relay autoreactivity between two separate compartments of MHC-restricted T cells, leading to inclusion of distinct B cell populations in germinal centers. Our findings demonstrate that B cells initiate and propagate the autoimmune response.

Novel Auger-Electron-Emitting 191Pt-Labeled Pyrrole-Imidazole Polyamide Targeting MYCN Increases Cytotoxicity and Cytosolic dsDNA Granules in MYCN-Amplified Neuroblastoma

Auger electrons can cause nanoscale physiochemical damage to specific DNA sites that play a key role in cancer cell survival. Radio-Pt is a promising Auger-electron source for damaging DNA efficiently because of its ability to bind to DNA. Considering that the cancer genome is maintained under abnormal gene amplification and expression, here, we developed a novel 191Pt-labeled agent based on pyrrole-imidazole polyamide (PIP), targeting the oncogene MYCN amplified in human neuroblastoma, and investigated its targeting ability and damaging effects. A conjugate of MYCN-targeting PIP and Cys-(Arg)3-coumarin was labeled with 191Pt via Cys (191Pt-MYCN-PIP) with a radiochemical purity of >99%. The binding potential of 191Pt-MYCN-PIP was evaluated via the gel electrophoretic mobility shift assay, suggesting that the radioagent bound to the DNA including the target sequence of the MYCN gene. In vitro assays using human neuroblastoma cells showed that 191Pt-MYCN-PIP bound to DNA efficiently and caused DNA damage, decreasing MYCN gene expression and MYCN signals in in situ hybridization analysis, as well as cell viability, especially in MYCN-amplified Kelly cells. 191Pt-MYCN-PIP also induced a substantial increase in cytosolic dsDNA granules and generated proinflammatory cytokines, IFN-α/β, in Kelly cells. Tumor uptake of intravenously injected 191Pt-MYCN-PIP was low and its delivery to tumors should be improved for therapeutic application. The present results provided a potential strategy, targeting the key oncogenes for cancer survival for Auger electron therapy.

Proteomic analyses reveal cystatin c is a promising biomarker for evaluation of systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease with multiple organ involvement, especially the kidneys. However, the underlying mechanism remains unclear, and accurate biomarkers are still lacking. This study aimed to identify biomarkers to assess organ damage and disease activity in patients with SLE using quantitative proteomics.

METHODS

Proteomic analysis was performed using mass spectrometry in 15 patients with SLE and 15 age-matched healthy controls. Proteomic profiles were compared in four main subtypes: SLE with proteinuria (SLE-PN), SLE without proteinuria (SLE-non-PN), SLE with anti-dsDNA positivity (SLE-DP), and SLE with anti-dsDNA negativity (SLE-non-DP). Gene ontology biological process analysis revealed differentially expressed protein networks. Cystatin C (CysC) levels were measured in 200 patients with SLE using an immunoturbidimetric assay. Clinical and laboratory data were collected to assess their correlation with serum CysC levels.

RESULTS

Proteomic analysis showed that upregulated proteins in both the SLE-PN and SLE-DP groups were mainly mapped to neutrophil activation networks. Moreover, CysC from neutrophil activation networks was upregulated in both the SLE-PN and SLE-DP groups. The associations of serum CysC level with proteinuria, anti-dsDNA positivity, lower complement C3 levels, and SLE disease activity index score in patients with SLE were further validated in a large independent cohort.

CONCLUSIONS

Neutrophil activation is more prominent in SLE with proteinuria and anti-dsDNA positivity, and CysC is a promising marker for monitoring organ damage and disease activity in SLE.

Irradiation Attenuates Systemic Lupus Erythematosus-Like Morbidity in NZBWF1 Mice: Focusing on CD180-Negative Cells

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies that can induce systemic inflammation. Ultraviolet-A and X-ray irradiation have been reported to have therapeutic effects in patients with SLE. We previously demonstrated that CD180-negative cells, these are radiosensitive, contribute to the development of SLE-like morbidity in NZBWF1 mice. In this study, the effects of irradiation on SLE-like morbidity manifestations in NZBWF1 mice and on CD180-negative cells were investigated. Whole-body irradiation, excluding the head, attenuated SLE-like morbidity in vivo, as indicated by the prevention of the renal lesion development, inhibition of anti-dsDNA antibody production, reduction of urinary protein levels, and prolongation of the lifespan. Irradiation also reduced the proportion of CD180-negative cells in the spleen. Although other immune cells or molecules may be triggered because of the whole-body irradiation treatment, previous research, and the current results suggest a strong relationship between the radiation-induced decrease in CD180-negative cells and the amelioration of SLE-like morbidities. Clinical trials assessing CD180-negative cells as a therapeutic target for SLE have been hampered by the lack of validated cell markers; nonetheless, the present findings suggest that radiotherapy may be a new therapeutic strategy for managing SLE symptoms.

Clinical Research of Lupus Retinopathy: Quantitative Analysis of Retinal Vessels by Optical Coherence Tomography Angiography in Patients with Systemic Lupus Erythematosus

BACKGROUND

Lupus retinopathy, an ocular manifestation of systemic lupus erythematosus (SLE), is the major pathology attributed to retinal vasculopathy. Our study is to analyze the changes in retinal vessels in patients with SLE by optical coherence tomography angiography.

METHODS

A total of 61 SLE patients without obvious retinal manifestation and 71 healthy people were included. The SLE patients were further divided into a lupus nephritis (LN) group and a non-LN group. The changes in central macular thickness (CMT) and the retinal vessel densities were compared between the two groups, and the correlation between retinal vascular changes and disease activity was analyzed.

RESULTS

Compared with healthy control, the CMT and the retinal vascular densities in both superficial and deep retina were decreased significantly in SLE patients. There was no significant difference in retinal vascular densities between LN groups and non-LN groups.

CONCLUSION

The CMT and retinal vessel densities were decreased in SLE patients without clinical manifestations, which might serve as a sensitive biomarker for early changes of lupus retinopathy in SLE patients.

Longitudinal study of patients with discrepant results in CLIFT and a solid-phase dsDNA antibody assay: does a gold standard dsDNA assay exist?

OBJECTIVE

Antidouble-stranded DNA (dsDNA) antibodies are essential for diagnosis and follow-up of systemic lupus erythematous (SLE). To ensure the best diagnostic approach, most healthcare laboratories opt for a combination of highly sensitive methods, such as solid-phase immunoassays, and highly specific methods, such as the Crithidia luciliae indirect immunofluorescence test (CLIFT). Even so, discordant results are common, thus hindering the diagnostic process. Therefore, this study aimed to characterise a cohort of patients with discrepant results for a dsDNA fluorescence enzyme immunoassay (FEIA) and CLIFT during 2016-2018 and to follow patients up until December 2021.

METHODS

We performed an observational, longitudinal and retrospective study on 417 samples from 257 patients who had been referred for suspected connective tissue diseases or followed up after diagnosis. All of them were positive for antinuclear antibodies (ANAs) using an indirect immunofluorescence assay (IFA) on Hep-2 cells, the entry criterion in our laboratory, and positive for FEIA dsDNA. Samples were then tested with CLIFT according to our routine protocol, which includes CLIFT testing after FEIA dsDNA results ≥10 UI/ml. After the assessment of data quality, the final analysis was based on 222 patients.

RESULTS

Eighty-three patients (37.4%) had positive results in both tests and met the diagnostic criteria for SLE. However, 139 patients (62.6%) had discrepant results (FEIA+, CLIFT-). Of these, 58 patients (41.7%) had a diagnosis of SLE, with 47 (33.8%) having been previously diagnosed and under treatment. The remaining 11 patients (7.9%) had a new diagnosis of SLE, which was made up within 4 years of the initial screening. A total of 81 of the 139 patients (57.5%) with discrepant results did not meet lupus criteria during the follow-up period.

CONCLUSIONS

The study showed that CLIFT could be negative in both treated and newly diagnosed SLE, thus underlining the importance of follow-up of dsDNA-positive results using solid-phase tests. Therefore, quantitative tests such as FEIA could add value to the diagnosis and management of patients with suspected SLE.

B cell polygenic risk scores associate with anti-dsDNA antibodies and nephritis in systemic lupus erythematosus

OBJECTIVE

B cell function and autoantibodies are important in SLE pathogenesis. In this work, we aimed to investigate the impact of cumulative SLE B cell genetics on SLE subphenotype and autoantibody profile.

METHODS

Female patients with SLE (n=1248) and healthy controls (n=400) were genotyped using Illumina's Global Screening Array. Two polygenic risk scores (PRSs), one representing B cell genes and the other B cell activation genes, were calculated for each individual using risk loci for SLE in genes assigned to B cell-related pathways according to the Kyoto Encyclopedia of Genes and Genomes, Gene Ontology and Reactome Databases.

RESULTS

Double-stranded DNA (dsDNA) antibodies were more prevalent among patients with a high compared with a low SLE B cell PRS (OR 1.47 (1.07 to 2.01), p=0.018), and effect sizes were augmented in patients with human leucocyte antigen (HLA) risk haplotypes HLA-DRB1*03:01 and HLA-DRB1*15:01 (DRB1*03/15 -/- (OR 0.99 (0.56 to 1.77), p=0.98; DRB1*03/15 +/- or -/+ (OR 1.64 (1.06 to 2.54), p=0.028; and DRB1*03/15 +/+ (OR 4.47 (1.21 to 16.47), p=0.024). Further, a high compared with a low B cell PRS was associated with low complement levels in DRB1*03/15 +/+ patients (OR 3.92 (1.22 to 12.64), p=0.022). The prevalence of lupus nephritis (LN) was higher in patients with a B cell activation PRS above the third quartile compared with patients below (OR 1.32 (1.00 to 1.74), p=0.048).

CONCLUSIONS

High genetic burden related to B cell function is associated with dsDNA antibody development and LN. Assessing B cell PRSs may be important in order to determine immunological pathways influencing SLE and to predict clinical phenotype.

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.

Prospects and Pitfalls of Plasma Complement C4 in Schizophrenia: Building a Better Biomarker

Complex brain disorders like schizophrenia may have multifactorial origins related to mis-timed heritable and environmental factors interacting during neurodevelopment. Infections, inflammation, and autoimmune diseases are over-represented in schizophrenia leading to immune system-centered hypotheses. Complement component C4 is genetically and neurobiologically associated with schizophrenia, and its dual activity peripherally and in the brain makes it an exceptional target for biomarker development. Studies to evaluate the biomarker potential of plasma or serum C4 in schizophrenia do so to understand how peripheral C4 might reflect central nervous system-derived neuroinflammation, synapse pruning, and other mechanisms. This effort, however, has produced mostly conflicting results, with peripheral C4 sometimes elevated, reduced, or unchanged between comparison groups. We undertook a pilot biomarker development study to systematically identify sociodemographic, genetic, and immune-related variables (autoimmune, infection-related, gastrointestinal, inflammatory), which may be associated with plasma C4 levels in schizophrenia (SCH; n = 335) and/or in nonpsychiatric comparison subjects (NCs; n = 233). As with previously inconclusive studies, we detected no differences in plasma C4 levels between SCH and NCs. In contrast, levels of general inflammation, C-reactive protein (CRP), were significantly elevated in SCH compared to NCs (ANOVA, F = 20.74, p < 0.0001), suggestive that plasma C4 and CRP may reflect different sources or causes of inflammation. In multivariate regressions of C4 gene copy number variants, plasma C4 levels were correlated only for C4A (not C4B, C4L, C4S) and only in NCs (R Coeff = 0.39, CI = 0.01-0.77, R2 = 0.18, p < 0.01; not SCH). Other variables associated with plasma C4 levels only in NCs included sex, double-stranded DNA IgG, tissue-transglutaminase (TTG) IgG, and cytomegalovirus IgG. Toxoplasma gondii IgG was the only variable significantly correlated with plasma C4 in SCH but not in NCs. Many variables were associated with plasma C4 in both groups (body mass index, race, CRP, N-methyl-D-aspartate receptor (NMDAR) NR2 subunit IgG, TTG IgA, lipopolysaccharide-binding protein (LBP), and soluble CD14 (sCD14). While the direction of most C4 associations was positive, autoimmune markers tended to be inverse, and associated with reduced plasma C4 levels. When NMDAR-NR2 autoantibody-positive individuals were removed, plasma C4 was elevated in SCH versus NCs (ANOVA, F = 5.16, p < 0.02). Our study was exploratory and confirmation of the many variables associated with peripheral C4 requires replication. Our preliminary results point toward autoimmune factors and exposure to the pathogen, T. gondii, as possibly significant contributors to variability of total C4 protein levels in plasma of individuals with schizophrenia.