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Background: Systemic sclerosis (SSc) is a multisystem autoimmune disorder that has an unclear etiology and disproportionately affects women and African Americans. Despite this, African Americans are dramatically underrepresented in SSc research. Additionally, monocytes show heightened activation in SSc and in African Americans relative to European Americans. In this study, we sought to investigate DNA methylation and gene expression patterns in classical monocytes in a health disparity population., Methods: Classical monocytes (CD14+ + CD16-) were FACS-isolated from 34 self-reported African American women. Samples from 12 SSc patients and 12 healthy controls were hybridized on MethylationEPIC BeadChip array, while RNA-seq was performed on 16 SSc patients and 18 healthy controls. Analyses were computed to identify differentially methylated CpGs (DMCs), differentially expressed genes (DEGs), and CpGs associated with changes in gene expression (eQTM analysis)., Results: We observed modest DNA methylation and gene expression differences between cases and controls. The genes harboring the top DMCs, the top DEGs, as well as the top eQTM loci were enriched for metabolic processes. Genes involved in immune processes and pathways showed a weak upregulation in the transcriptomic analysis. While many genes were newly identified, several other have been previously reported as differentially methylated or expressed in different blood cells from patients with SSc, supporting for their potential dysregulation in SSc., Conclusions: While contrasting with results found in other blood cell types in largely European-descent groups, the results of this study support that variation in DNA methylation and gene expression exists among different cell types and individuals of different genetic, clinical, social, and environmental backgrounds. This finding supports the importance of including diverse, well-characterized patients to understand the different roles of DNA methylation and gene expression variability in the dysregulation of classical monocytes in diverse populations, which might help explaining the health disparities., (© 2023. The Author(s).)

Objectives: Families that contain multiple siblings affected with childhood onset of systemic lupus erythematosus (SLE) likely have strong genetic predispositions. We performed whole exome sequencing (WES) to identify familial rare risk variants and to assess their effects in lupus., Methods: Sanger sequencing validated the two ultra-rare, predicted pathogenic risk variants discovered by WES and identified additional variants in 562 additional patients with SLE. Effects of a splice site variant and a frameshift variant were assessed using a Minigene assay and CRISPR/Cas9-mediated knock-in (KI) mice, respectively., Results: The two familial ultra-rare, predicted loss-of-function (LOF) SAT1 variants exhibited X-linked recessive Mendelian inheritance in two unrelated African-American families. Each LOF variant was transmitted from the heterozygous unaffected mother to her two sons with childhood-onset SLE. The p.Asp40Tyr variant affected a splice donor site causing deleterious transcripts. The young hemizygous male and homozygous female Sat1 p.Glu92Leufs*6 KI mice spontaneously developed splenomegaly, enlarged glomeruli with leucocyte infiltration, proteinuria and elevated expression of type I interferon-inducible genes. SAT1 is highly expressed in neutrophils and encodes spermidine/spermine-N 1 -acetyltransferase 1 (SSAT1), a rate-limiting enzyme in polyamine catabolism. Young male KI mice exhibited neutrophil defects and decreased proportions of Foxp3 +CD4+ T-cell subsets. Circulating neutrophil counts and proportions of Foxp3 +CD4+ T cells correlated with decreased plasma levels of spermine in treatment-naive, incipient SLE patients., Conclusions: We identified two novel SAT1 LOF variants, showed the ability of the frameshift variant to confer murine lupus, highlighted the pathogenic role of dysregulated polyamine catabolism and identified SAT1 LOF variants as new monogenic causes for SLE., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Oestrogen and oestrogen receptor alpha (ERα) have been implicated in systemic lupus erythematosus pathogenesis. ERα signalling influences dendritic cell (DC) development and function, as well as inflammation and downstream immune responses. We previously reported that ERα modulates multiple Toll-like receptor-stimulated pathways in both conventional and plasmacytoid DCs in lupus-prone mice. For example, CD11c hi MHCII + cell numbers are reduced in mice with global ERα deficiency or when expressing a short variant of ERα. Herein, RNA-seq analysis of CD11c hi cells from bone marrow of NZM2410 mice expressing WT ERα versus ERα short versus ERα null revealed differentially expressed complement genes, interferon-related genes and cytokine signalling (e.g., IL-17 and Th17 pathways). To better understand the role of ERα in CD11c + cells, lupus prone NZM2410 mice with selective deletion of the Esr1 gene in CD11c + cells were generated. Phenotype and survival of these mice were similar with the exception of Cre positive (CrePos) female mice. CrePos females, but not males, all died unexpectedly prior to 35 weeks. DC subsets were not significantly different between groups. Since ERα is necessary for robust development of DCs, this result suggests that DC fate was determined prior to CD11c expression and subsequent ERα deletion (i.e., proximally in DC ontogeny). Overall, findings point to a clear functional role for ERα in regulating cytokine signalling and inflammation, suggesting that further study into ERα-mediated regulatory mechanisms in DCs and other immune cell types is warranted., (© 2022 John Wiley & Sons Ltd.)

Objectives: There is an intricate interplay between the microbiome and the immune response impacting development of normal immunity and autoimmunity. However, we do not fully understand how the microbiome affects production of natural-like and pathogenic autoantibodies. Peptidoglycan (PGN) is a component of the bacterial cell wall which is highly antigenic. PGNs from different bacteria can differ in their immune regulatory activities., Methods: C57BL/6 and MRL/lpr mice were intraperitoneally injected with saline or PGN from Staphylococcus aureus or Bacillus subtilis. Spleen anti-double-stranded DNA (dsDNA) IgG + B cells were sorted for B-cell receptor sequencing. Serum autoantibody levels and kidney damage were analyzed. Further, the association between plasma S. aureus translocation and systemic lupus erythematosus (SLE) pathogenesis was assessed in women., Results: Administration of B. subtilis PGN induced natural-like anti-dsDNA autoantibodies (e.g., IgM, short lived IgG response, and no tissue damage), whereas S. aureus PGN induced pathogenic anti-dsDNA autoantibodies (e.g., prolonged IgG production, low IgM, autoantibody-mediated kidney damage) in C57BL/6 and/or MRL/lpr mice. However, serum total IgG did not differ. S. aureus PGN induced antibodies with reduced clonality and greater hypermutation of IGHV3-74 in splenic anti-dsDNA IgG + B cells from C57BL/6 mice. Further, S. aureus PGN promoted IgG class switch recombination via toll-like receptor 2. Plasma S. aureus DNA levels were increased in women with SLE versus control women and correlated with levels of lupus-related autoantibodies and renal involvement., Conclusions: S. aureus PGN induces pathogenic autoantibody production, whereas B. subtilis PGN drives production of natural nonpathogenic autoantibodies., (Published by Elsevier Ltd.)

Systemic lupus erythematosus (SLE) is propelled by pathogenic autoantibody (AutoAb) and immune pathway dysregulation. Identifying populations at risk of reaching classified SLE is essential to curtail inflammatory damage. Lupus blood relatives (Rel) have an increased risk of developing SLE. We tested factors to identify Rel at risk of developing incomplete lupus (ILE) or classified SLE vs. clinically unaffected Rel and healthy controls (HC), drawing from two unique, well characterized lupus cohorts, the lupus autoimmunity in relatives (LAUREL) follow-up cohort, consisting of Rel meeting <4 ACR criteria at baseline, and the Lupus Family Registry and Repository (LFRR), made up of SLE patients, lupus Rel, and HC. Medical record review determined ACR SLE classification criteria; study participants completed the SLE portion of the connective tissue disease questionnaire (SLE-CSQ), type 2 symptom questions, and provided samples for assessment of serum SLE-associated AutoAb specificities and 52 plasma immune mediators. Elevated SLE-CSQ scores were associated with type 2 symptoms, ACR scores, and serology in both cohorts. Fatigue at BL was associated with transition to classified SLE in the LAUREL cohort ( p≤0.01 ). Increased levels of BLyS and decreased levels of IL-10 were associated with type 2 symptoms (p <0.05 ). SLE-CSQ scores, ACR scores, and accumulated AutoAb specificities correlated with levels of multiple inflammatory immune mediators ( p<0.05 ), including BLyS, IL-2Rα, stem cell factor (SCF), soluble TNF receptors, and Th-1 type mediators and chemokines. Transition to SLE was associated with increased levels of SCF ( p<0.05 ). ILE Rel also had increased levels of TNF-α and IFN-γ, offset by increased levels of regulatory IL-10 and TGF-β ( p<0.05 ). Clinically unaffected Rel (vs. HC) had higher SLE-CSQ scores ( p<0.001 ), increased serology ( p<0.05 ), and increased inflammatory mediator levels, offset by increased IL-10 and TGF-β ( p<0.01 ). These findings suggest that Rel at highest risk of transitioning to classified SLE have increased inflammation coupled with decreased regulatory mediators. In contrast, clinically unaffected Rel and Rel with ILE demonstrate increased inflammation offset with increased immune regulation, intimating a window of opportunity for early intervention and enrollment in prevention trials., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Munroe, Young, Guthridge, Kamen, Gilkeson, Weisman, Ishimori, Wallace, Karp, Harley, Norris and James.)

Objective: Blood microbiome has been analyzed in cancer patients using machine learning. We aimed to study whether the plasma microbiome represents the microbial community in the gut among patients with systemic lupus erythematosus (SLE) and healthy controls (HCs)., Methods: Paired plasma and stool samples from female patients with SLE and female HCs were assessed for microbiome composition by microbial 16S ribosomal RNA sequencing., Results: Decreased microbial alpha diversity in stool compared to plasma and distinct plasma and gut beta diversity were found in both HCs and patients with SLE. No difference in gut microbial diversity was found; however, plasma alpha diversity was decreased in patients with SLE compared to HCs. The predominant bacteria differed between plasma and stool in both groups. Although the predominant plasma and stool genus bacteria were similar in patients with SLE and HCs, some were clearly different., Conclusion: Compared to the gut, the plasma microbiome contained distinct community and greater heterogeneity, indicating that the predominant circulating microbiome may originate from sites (eg, oral or skin) other than the gastrointestinal tract. The decreased plasma but not gut alpha diversity in patients with SLE compared to HCs implies an altered plasma microbiome in SLE, which may be important for systemic immune perturbations and SLE disease pathogenesis., (Copyright © 2022 by the Journal of Rheumatology.)

Although a number of new immunosuppressive agents and biologics have been approved for treating various autoimmune inflammatory rheumatic diseases, there remains a substantial number of patients who have no clinical response or limited clinical response to these available treatments. Use of cellular therapies is a novel approach for the treatment of autoimmune inflammatory rheumatic diseases, with perhaps enhanced efficacy and less toxicity than current therapies. Autologous hematopoietic stem cell transplants were the first foray into cellular therapies, with proven efficacy in scleroderma and multiple sclerosis. Newer, yet unproven, cellular therapies include allogeneic mesenchymal stromal cells, which have been shown to be effective in graft-versus-host disease and in healing Crohn's fistulas. Chimeric antigen receptor T cells are effective in various malignancies, with possible application in rheumatic diseases, as shown in preclinical studies in murine lupus and recently in human lupus. Treg cells are one of the master controllers of the immune response and are decreased in number and/or effectiveness in specific autoimmune diseases. Expansion of autologous Treg cells is an attractive approach to controlling autoimmunity. There are a number of other regulatory cells in the immune system, including Breg cells, dendritic cells, macrophages, and other T cell types, that are in early stages of development as treatments. In this review, the current evidence for the efficacy and mechanisms of actions of cellular therapies already in use or in clinical trials in human autoimmune diseases will be discussed, including the limitations of these therapies and potential side effects., (© 2022 American College of Rheumatology.)

Objective: Elevated interleukin-10 (IL-10) levels in patients with systemic lupus erythematosus (SLE) have B cell-promoting effects, contributing to autoantibody production and tissue damage. We aimed to characterize up-regulated IL-10+ B cell subsets and dysregulated IL10 expression in SLE B cells for new therapeutic options., Methods: Proportions of Th10 and IL-10+ B cell subsets in peripheral blood mononuclear cells (PBMCs) were assessed using flow cytometry. The IL10 3'-untranslated region (3'-UTR) dual-luciferase vector was constructed and cotransfected with small interfering RNA (siRNA), microRNA (miRNA) mimics, or miRNA inhibitors into Raji cells. Transcript levels were quantified using TaqMan assays., Results: Culture conditions that induced IL-10+ Breg cells in healthy controls resulted in expansion of IL-10+ double-negative 2 (DN2; IgD-CD27-CD21-CD11c+) B cells in SLE PBMCs. Proportions of IL-10+ DN2, but not those of IL-10- DN2, correlated with disease activity and levels of antibodies to double-stranded DNA (dsDNA) (r = 0.60, P = 0.03 for cohort 1; r = 0.38, P = 0.03 for cohort 2), and were associated with high levels or seropositivity of anti-Sm (P = 0.03 for cohort 1; P = 0.01 for cohort 2) and IgG anticardiolipin (P < 0.01 for cohort 1; P = 0.02 for cohort 2) in SLE patients from 2 cohorts, of mainly African American subjects (cohort 1) and of Asian subjects (cohort 2). Proportions of Th10 (CD45RA-CXCR5-CXCR3+PD-1 high CD4+) cells correlated with IL-10+ DN2 frequencies (r = 0.60, P < 0.01 for cohort 2), antinuclear antibody titers (r = 0.52, P = 0.01 for cohort 2), and proteinuria levels (r = 0.72, P < 0.01 for cohort 2) in SLE patients. Screening of predicted IL10 3'-UTR-targeting miRNAs in SLE B cells identified miRNA-17-5p (miR-17-5p) and miR-20a-5p, with their levels inversely correlated with IL10 (r = -0.47, P < 0.01 for miR-17-5p; r = -0.37, P = 0.03 for miR-20-5p) and transcription factor E2F2 (r = -0.48, P = 0.04 for miR-17-5p; r = -0.45, P = 0.05 for miR-20-5p). In Raji cells, knockdown of E2F2 expression resulted in increased levels of miR-17-5p and miR-20a-5p and decreased IL10 messenger RNA (mRNA) and protein levels, and overexpression and inhibition of miR-17-5p down-regulated and up-regulated, respectively, IL10 mRNA levels, suggesting regulation of IL10 expression by an E2F2-miR-17-5p loop., Conclusion: IL-10 promotes extrafollicular autoimmune responses in patients with active SLE, which might be dampened by targeting the E2F2-miR-17-5p circuitry., (© 2021 American College of Rheumatology.)

Objectives: We previously identified a hypomorphic variant, p.Arg90His (p.R90H) of neutrophil cytosolic factor 1 ( NCF1, a regulatory subunit of phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 complex), as an putative causal variant for systemic lupus erythematosus (SLE), and established a knock-in (KI) H90 variant in the C57BL/6 background to study how this variant promotes lupus development., Methods: Wild type (WT) and KI littermates were assessed for immune profiles and lupus-like features. Disease activity and renal damage of patients with SLE were assessed by systemic lupus erythematosus disease activity index (SLEDAI) and renal items of systemic lupus international collaborating clinics (SLICC), respectively., Results: Compared with WT littermates, 5-week-old homozygous KI mice had reduced oxidative burst, splenomegaly, elevated type I interferon (IFN-I) scores, increased ratios of splenic follicular T helper 2 (Tfh2) to either T follicular regulatory (Tfr) or Tfh1 cells, increased ANA + follicular, germinal centre and plasma cells without spontaneous kidney disease up to 1 year of age. Pristane treatment exacerbated the immune dysregulation and induced IFN-I-dependent kidney disease in 36-week-old H90 KI female mice. Decreased efferocytosis of macrophages derived from KI mice and patients with homozygous H90 SLE promoted elevated ratios of Tfh2/Tfr and Tfh2/Tfh1 as well as dysregulated humoral responses due to reduced voltage-gated proton channel 1 (Hv1)-dependent acidification of phagosome pH to neutralise the decreased electrogenic effect of the H90 variant, resulting in impaired maturation and phagosome proteolysis, and increased autoantibody production and kidney damage in mice and patients with SLE of multiple ancestries., Conclusions: A lupus causal variant, NCF1-H90, reduces macrophage efferocytosis, enhances Tfh2 responses and promotes autoantibody production and kidney damage in both mice and patients with SLE., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)