Synovial Tissue Heterogeneity in Japanese Patients With Rheumatoid Arthritis Elucidated Using a Cell-Type Deconvolution Approach.

OBJECTIVE: Recent advances in single-cell RNA sequencing technology have improved our understanding of the immunological landscape of rheumatoid arthritis (RA). We aimed to stratify the synovium from East Asian patients with RA by immune cell compositions and gain insight into the inflammatory drivers of each synovial phenotype. METHODS: Synovial tissues were obtained from East Asian patients in Japan with RA (n = 41) undergoing articular surgery. The cellular composition was quantified by a deconvolution approach using a public single-cell-based reference. Inflammatory pathway activity was calculated by gene set variation analysis, and chromatin accessibility was evaluated using assay of transposase accessible chromatin-sequencing. RESULTS: We stratified RA synovium into three distinct subtypes based on the hierarchical clustering of cellular composition data. One subtype was characterized by abundant HLA-DRAhigh synovial fibroblasts, autoimmune-associated B cells, GZMK+ GZMB+ CD8+ T cells, interleukin (IL)1-ß+ monocytes, and plasmablasts. In addition, tumor necrosis factor (TNF)-α, interferons (IFNs), and IL-6 signaling were highly activated in this subtype, and the expression of various chemokines was significantly enhanced. Moreover, we found an open chromatin region overlapping with RA risk locus rs9405192 near the IRF4 gene, suggesting the genetic background influences the development of this inflammatory synovial state. The other two subtypes were characterized by increased IFNs and IL-6 signaling, and expression of molecules associated with degeneration, respectively. CONCLUSION: This study adds insights into the synovial heterogeneity in East Asian patients and shows a promising link with predominant inflammatory signals. Evaluating the site of inflammation has the potential to lead to appropriate drug selection that matches the individual pathology.

Transcriptome analysis of immune cells from Behçet's syndrome patients: the importance of IL-17-producing cells and antigen-presenting cells in the pathogenesis of Behçet's syndrome.

BACKGROUND: Behçet's syndrome (BS) is an immune-mediated disease characterized by recurrent oral ulcers, genital ulcers, uveitis, and skin symptoms. HLA-B51, as well as other genetic polymorphisms, has been reported to be associated with BS; however, the pathogenesis of BS and its relationship to genetic risk factors still remain unclear. To address these points, we performed immunophenotyping and transcriptome analysis of immune cells from BS patients and healthy donors. METHODS: ImmuNexUT is a comprehensive database consisting of RNA sequencing data and eQTL database of immune cell subsets from patients with immune-mediated diseases and healthy donors, and flow cytometry data and transcriptome data from 23 BS patients and 28 healthy donors from the ImmuNexUT study were utilized for this study. Differential gene expression analysis and weighted gene co-expression network analysis (WGCNA) were performed to identify genes associated with BS and clinical features of BS. eQTL database was used to assess the relationship between genetic risk factors of BS with those genes. RESULTS: The frequency of Th17 cells was increased in BS patients, and transcriptome analysis of Th17 cells suggested the activation of the NFκB pathway in Th17 cells of BS patients. Next, WGCNA was used to group genes into modules with similar expression patterns in each subset. Modules of antigen-presenting cells were associated with BS, and pathway analysis suggested the activation of antigen-presenting cells of BS patients. Further examination of genes in BS-associated modules indicated that the expression of YBX3, a member of a plasmacytoid dendritic cell (pDC) gene module associated with BS, is influenced by a BS risk polymorphism, rs2617170, in pDCs, suggesting that YBX3 may be a key molecule connecting genetic risk factors of BS with disease pathogenesis. Furthermore, pathway analysis of modules associated with HLA-B51 indicated that the association of IL-17-associated pathways in memory CD8+ T cells with HLA-B51; therefore, IL-17-producing CD8+ T cells, Tc17 cells, may play a critical role in BS. CONCLUSIONS: Various cells including CD4+ T cells, CD8+ T cells, and antigen-presenting cells are important in the pathogenesis of BS. Tc17 cells and YBX3 may be potential therapeutic targets in BS.

Aseptic Cavernosal Abscess: An Unrecognized Feature of Neutrophilic Dermatosis.

A 50-year-old man developed a sterile cavernosal abscess followed by prominent features of necrotizing neutrophilic dermatosis. We conducted a literature review, which revealed that aseptic abscesses in the corpus cavernosum occur in association with neutrophilic dermatosis. Patients with this condition frequently receive unnecessary antibiotic treatment and surgical interventions. Although this condition responds to systemic corticosteroids, the functional prognosis of the penis is poor. Abscess formation may be the initial presentation of neutrophilic dermatoses, and underlying conditions may even be absent. Clinicians need to be aware of this condition to distinguish it from bacterial infection and initiate early disease-specific treatments.

Acute Liver Failure Due to Hypereosinophilic Syndrome Accompanied by Duodenal Perforation.

A 78-year-old woman presenting with severe acute liver failure was admitted to our hospital. On screening for the etiology of acute liver failure, it was diagnosed as being due to idiopathic hypereosinophilic syndrome (eosinophil count reported as 4766/µL; 33.8% of the white blood cells). Her medical history included marked eosinophilia, as observed six months prior to this admission. Corticosteroid therapy was initiated. During the clinical course, duodenal perforation occurred but was managed promptly by appropriate surgery. A liver biopsy, following the initiation of corticosteroid therapy, revealed degenerating hepatic cells with mild eosinophilic infiltration. With corticosteroid therapy, the liver function improved.

Dynamic landscape of immune cell-specific gene regulation in immune-mediated diseases.

Genetic studies have revealed many variant loci that are associated with immune-mediated diseases. To elucidate the disease pathogenesis, it is essential to understand the function of these variants, especially under disease-associated conditions. Here, we performed a large-scale immune cell gene-expression analysis, together with whole-genome sequence analysis. Our dataset consists of 28 distinct immune cell subsets from 337 patients diagnosed with 10 categories of immune-mediated diseases and 79 healthy volunteers. Our dataset captured distinctive gene-expression profiles across immune cell types and diseases. Expression quantitative trait loci (eQTL) analysis revealed dynamic variations of eQTL effects in the context of immunological conditions, as well as cell types. These cell-type-specific and context-dependent eQTLs showed significant enrichment in immune disease-associated genetic variants, and they implicated the disease-relevant cell types, genes, and environment. This atlas deepens our understanding of the immunogenetic functions of disease-associated variants under in vivo disease conditions.

Identifying the most influential gene expression profile in distinguishing ANCA-associated vasculitis from healthy controls.

OBJECTIVE: Previous gene expression analyses seeking genes specific to antineutrophil cytoplasmic antibody-associated vasculitis (AAV) have been limited due to crude cell separation and the use of microarrays. This study aims to identify AAV-specific gene expression profiles in a way that overcomes those limitations. METHODS: Blood samples were collected from 26 AAV patients and 28 healthy controls (HCs). Neutrophils were isolated by negative selection, whereas 19 subsets of peripheral blood mononuclear cells were sorted by fluorescence assisted cell sorting. RNA-sequencing was then conducted for each sample, and iterative weighted gene correlation network analysis (iterativeWGCNA) and random forest were consecutively applied to identify the most influential gene module in distinguishing AAV from HCs. Correlations of the identified module with clinical parameters were evaluated, and the biological role was assessed with hub gene identification and pathway analysis. Particularly, the module's association with neutrophil extracellular trap formation, NETosis, was analyzed. Finally, the module's overlap with GWAS-identified autoimmune disease genes (GADGs) was assessed for validation. RESULTS: A neutrophil module (Neu_M20) was ranked top in the random forest analysis among 255 modules created by iterativeWGCNA. Neu_M20 correlated with disease activity and neutrophil counts but not with the presence of antineutrophil cytoplasmic antibody. The module comprised pro-inflammatory genes, including those related to NETosis, supported by experimental evidence. The genes in the module significantly overlapped GADGs. CONCLUSION: We identified the distinct group of pro-inflammatory genes in neutrophils, which characterize AAV. Further investigations are warranted to confirm our findings as they could serve as novel therapeutic targets.

Integrated bulk and single-cell RNA-sequencing identified disease-relevant monocytes and a gene network module underlying systemic sclerosis.

OBJECTIVE: Immunological disturbances have been reported in systemic sclerosis (SSc). This study assessed the transcriptome disturbances in immune cell subsets in SSc and characterized a disease-related gene network module and immune cell cluster at single cell resolution. METHODS: Twenty-one Japanese SSc patients were enrolled and compared with 13 age- and sex-matched healthy controls (HC). Nineteen peripheral blood immune cell subsets were sorted by flow cytometry and bulk RNA-seq analysis was performed for each. Differential expression and pathway analyses were conducted. Iterative weighted gene correlation network analysis (iWGCNA) of each subset revealed clustered co-expressed gene network modules. Random forest analysis prioritized a disease-related gene module. Single cell RNA-seq analysis of 878 monocytes was integrated with bulk RNA-seq analysis and with a public database for single cell RNA-seq analysis of SSc patients. RESULTS: Inflammatory pathway genes were differentially expressed in widespread immune cell subsets of SSc. An inflammatory gene module from CD16+ monocytes, which included KLF10, PLAUR, JUNB and JUND, showed the greatest discrimination between SSc and HC. One of the clusters of SSc monocytes identified by single-cell RNA-seq analysis characteristically expressed these inflammatory co-expressed genes and was similar to lung infiltrating FCN1hi monocytes expressing IL1B. CONCLUSIONS: Our integrated analysis of bulk and single cell RNA-seq analysis identified an inflammatory gene module and a cluster of monocytes that are relevant to SSc pathophysiology. They could serve as candidate novel therapeutic targets in SSc.

Serum phosphatidylserine-specific phospholipase A1 as a novel biomarker for monitoring systemic lupus erythematosus disease activity.

AIM: To assess the utility of serum levels of phosphatidylserine-specific phospholipase A1 (PS-PLA1 ), a lipase involved in the production of lysophosphatidylserine with multi-immunomodulatory effects, in systemic lupus erythematosus (SLE). METHOD: Serum PS-PLA1 was measured in 161 patients with SLE (including 54 untreated patients), 80 disease controls (35 active rheumatoid arthritis [RA], 23 Sjögren's syndrome [SS], and 22 systemic sclerosis [SSc]), and 237 healthy controls. RESULTS: Serum PS-PLA1 was significantly higher in SLE patients than in healthy controls, RA and SS patients. Although PS-PLA1 was significantly elevated in SSc and SS patients compared with healthy controls, PS-PLA1 was significantly higher in untreated SLE patients than in treated SLE patients and disease control patients. Receiver operating characteristic analysis revealed that a cut-off value of 18.2 ng/mL distinguished untreated SLE from disease control, with sensitivity and specificity of 71.4% and 57.5%, respectively. PS-PLA1 was significantly correlated with SLE Disease Activity Index (SLEDAI) and immunoglobulin G (IgG), and inversely correlated with white blood cell counts, lymphocyte counts, total complement hemolytic activity (CH50), complements C3, and C4 in SLE patients overall. Stepwise multiple regression identified SLEDAI, CH50, and IgG as significant parameters. In SLEDAI-based disease activity groups, PS-PLA1 was significantly higher in SLE patients with high disease activity than in those with low disease activity. PS-PLA1 decreased significantly in parallel with SLEDAI in 35 SLE patients whose paired serum samples were available pre- and post-treatment. CONCLUSION: Serum PS-PLA1 is associated with disease activity of SLE, indicating its possible use as a biomarker for monitoring SLE disease activity.

Thoracic intradural extramedullary lesions causing progressive myelopathy as an initial manifestation of granulomatosis with polyangiitis: a case report and review of literature.

CONTEXT: To our knowledge, only a few reports regarding the spinal involvement of granulomatosis with polyangiitis (GPA)-also termed as Wegener's granulomatosis-have been published. However, all these cases reportedly exhibited epidural tumor-like lesions or dural thickening. FINDINGS: We report the case of a 57-year-old woman with progressive myelopathy caused by multiple spinal lesions with GPA, which appeared to be protruding inwards, within the dura mater, on magnetic resonance imaging (MRI); these lesions were difficult to distinguish from intradural tumors. Moreover, these lesions exhibited low intensity on both T1- and T2-weighted MRI, and showed prominent enhancement on gadolinium-contrast imaging. Resection biopsy was effective for both diagnosis and the recovery of the neurological deficit. CONCLUSION: Based on these findings, we suggest that GPA lesions can exhibit variable patterns in the spine. Nevertheless, clinicians should consider the possibility of GPA in such cases, particularly when multiple, inwardly protruding tumor-like lesions are detected within the dura mater on MRI.