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.

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.

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.