Epigenetic targets of Janus kinase inhibitors are linked to genetic risks of rheumatoid arthritis.

BACKGROUND: Current strategies that target cytokines (e.g., tumor necrosis factor (TNF)-α), or signaling molecules (e.g., Janus kinase (JAK)) have advanced the management for allergies and autoimmune diseases. Nevertheless, the molecular mechanism that underpins its clinical efficacy have largely remained elusive, especially in the local tissue environment. Here, we aimed to identify the genetic, epigenetic, and immunological targets of JAK inhibitors (JAKis), focusing on their effects on synovial fibroblasts (SFs), the major local effectors associated with destructive joint inflammation in rheumatoid arthritis (RA). METHODS: SFs were activated by cytokines related to inflammation in RA, and were treated with three types of JAKis or a TNF-α inhibitor (TNFi). Dynamic changes in transcriptome and chromatin accessibility were profiled across samples to identify drug targets. Furthermore, the putative targets were validated using luciferase assays and clustered regularly interspaced short palindromic repeat (CRISPR)-based genome editing. RESULTS: We found that both JAKis and the TNFi targeted the inflammatory module including IL6. Conversely, specific gene signatures that were preferentially inhibited by either of the drug classes were identified. Strikingly, RA risk enhancers for CD40 and TRAF1 were distinctively regulated by JAKis and the TNFi. We performed luciferase assays and CRISPR-based genome editing, and successfully fine-mapped the single causal variants in these loci, rs6074022-CD40 and rs7021049-TRAF1. CONCLUSIONS: JAKis and the TNFi had a direct impact on different RA risk enhancers, and we identified nucleotide-resolution targets for both drugs. Distinctive targets of clinically effective drugs could be useful for tailoring the application of these drugs and future design of more efficient treatment strategies.

Egr2 drives the differentiation of Ly6Chi monocytes into fibrosis-promoting macrophages in metabolic dysfunction-associated steatohepatitis in mice.

Metabolic dysfunction-associated steatohepatitis (MASH), previously called non-alcoholic steatohepatitis (NASH), is a growing concern worldwide, with liver fibrosis being a critical determinant of its prognosis. Monocyte-derived macrophages have been implicated in MASH-associated liver fibrosis, yet their precise roles and the underlying differentiation mechanisms remain elusive. In this study, we unveil a key orchestrator of this process: long chain saturated fatty acid-Egr2 pathway. Our findings identify the transcription factor Egr2 as the driving force behind monocyte differentiation into hepatic lipid-associated macrophages (hLAMs) within MASH liver. Notably, Egr2-deficiency reroutes monocyte differentiation towards a macrophage subset resembling resident Kupffer cells, hampering hLAM formation. This shift has a profound impact, suppressing the transition from benign steatosis to liver fibrosis, demonstrating the critical pro-fibrotic role played by hLAMs in MASH pathogenesis. Long-chain saturated fatty acids that accumulate in MASH liver emerge as potent inducers of Egr2 expression in macrophages, a process counteracted by unsaturated fatty acids. Furthermore, oral oleic acid administration effectively reduces hLAMs in MASH mice. In conclusion, our work not only elucidates the intricate interplay between saturated fatty acids, Egr2, and monocyte-derived macrophages but also highlights the therapeutic promise of targeting the saturated fatty acid-Egr2 axis in monocytes for MASH management.

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.

Functional evaluation of rare OASL variants by analysis of SLE patient-derived iPSCs.

BACKGROUND: Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease characterized by genetic heterogeneity and an interferon (IFN) signature. The overall landscapes of the heritability of SLE remains unclear. OBJECTIVES: To identify and elucidate the biological functions of rare variants underlying SLE, we conducted analyses of patient-derived induced pluripotent stem cells (iPSCs) in combination with genetic analysis. METHODS: Two familial SLE patient- and two healthy donor (HD)-derived iPSCs were established. Type 1 IFN-secreting dendritic cells (DCs) were differentiated from iPSCs. Genetic analyses of SLE-iPSCs, and 117 SLE patients and 107 HDs in the ImmuNexUT database were performed independently. Genome editing of the variants on iPSCs was performed with the CRISPR/Cas9 system. RESULTS: Type 1 IFN secretion was significantly increased in DCs differentiated from SLE-iPSCs compared to HD-iPSCs. Genetic analyses revealed a rare variant in the 2'-5'-Oligoadenylate Synthetase Like (OASL) shared between SLE-iPSCs and another independent SLE patient, and significant accumulation of OASL variants among SLE patients (HD 0.93%, SLE 6.84%, OR 8.387) in the database. Genome editing of mutated OASL 202Q to wild-type 202 R or wild-type OASL 202 R to mutated 202Q resulted in reduced or enhanced Type 1 IFN secretion of DCs. Three other OASL variants (R60W, T261S and A447V) accumulated in SLE patients had also capacities to enhance Type 1 IFN secretion in response to dsRNA. CONCLUSIONS: We established a patient-derived iPSC-based strategy to investigate the linkage of genotype and phenotype in autoimmune diseases. Detailed case-based investigations using patient-derived iPSCs provide information to unveil the heritability of the pathogenesis of autoimmune diseases.

Significance of anti-transcobalamin receptor antibodies in cutaneous arteritis revealed by proteome-wide autoantibody screening.

Cutaneous arteritis (CA) is a single-organ vasculitis that exclusively affects the small to medium-sized arteries of the skin. Diagnosis depends on a histological investigation with skin biopsy, which could be burdensome for both patients and clinicians. Moreover, the pathogenesis of CA remains unstudied, and treatment has not yet been established. Herein, we applied our proteome-wide autoantibody screening method to explore autoantibodies in the serum of CA patients. As a result, anti-transcobalamin receptor (TCblR) antibodies (Abs) were specifically detected in 24% of CA patients. Patients with positive anti-TCblR Abs were spared from peripheral neuropathy compared to those with negative anti-TCblR Abs, showing characteristics as CA confined to the skin. In addition, we revealed that anti-TCblR Abs trigger the autocrine loop of interleukin-6 mediated by tripartite motif-containing protein 21 in human endothelial cells and induce periarterial inflammation in murine skin. Furthermore, we demonstrated that methylcobalamin, a ligand of TCblR, ameliorates inflammation caused by anti-TCblR Abs both in vitro and in vivo. Collectively, our investigation unveils the pathologic significance of anti-TCblR Abs in CA and their potential as a diagnostic marker and a pathophysiology-oriented therapeutic target.

Transcriptome Profiling of Immune Cell Types in Peripheral Blood Reveals Common and Specific Pathways Involved in the Pathogenesis of Myositis-Specific Antibody-Positive Inflammatory Myopathies.

OBJECTIVE: Idiopathic inflammatory myopathies (IIM) demonstrate characteristic clinical phenotypes depending on the myositis-specific antibody (MSAs) present. We aimed to identify common or MSA-specific immunological pathways in different immune cell types from peripheral blood by transcriptome analysis. METHODS: We recruited 33 patients with IIM who were separated into the following groups: 15 patients with active disease at onset and 18 with inactive disease under treatment. All patients were positive for MSAs: anti-melanoma differentiation-associated gene 5 (MDA5) antibody (Ab) in 10 patients, anti-Mi-2 Ab in 7, and anti-aminoacyl-transfer RNA synthetase (ARS) Ab in 16. The patients were compared with 33 healthy controls. Twenty-four immune cell types sorted from peripheral blood were analyzed by flow cytometry, RNA sequencing, and differentially expressed gene analysis combined with pathway analysis. RESULTS: The frequencies of memory B cell types were significantly decreased in active patients, and the frequency of plasmablasts was prominently increased in active patients with anti-MDA5 Ab in comparison with healthy controls. The expression of type I interferon (IFN)-stimulated genes of all immune cell types was increased in the active, but not inactive, patients. Endoplasmic reticulum stress-related genes in all IIM memory B cells and oxidative phosphorylation-related genes in inactive IIM double negative B cells were also increased, suggesting prominent B cell activation in IIM. Furthermore, active patients with anti-MDA5 Ab, anti-Mi-2 Ab, or anti-ARS Ab were distinguished by IFN-stimulated and oxidative phosphorylation-related gene expression in plasmablasts. CONCLUSION: Unique gene expression patterns in patients with IIM with different disease activity levels and MSA types suggest different pathophysiologies. Especially, B cells may contribute to common and MSA-specific immunological pathways in IIM.

Autotaxin is a potential link between genetic risk factors and immunological disturbances of plasmacytoid dendritic cells in systematic lupus erythematosus.

BACKGROUND: The importance of autotaxin, an enzyme that catalyzes lysophospholipid production, has recently been recognized in various diseases, including cancer and autoimmune diseases. Herein, we examined the role of autotaxin in systemic lupus erythematosus (SLE), utilizing data from ImmuNexUT, a comprehensive database consisting of transcriptome data and expression quantitative trait locus (eQTL) data of immune cells from patients with immune-mediated disorders. METHODS: Serum autotaxin concentrations in patients with SLE and healthy controls (HCs) were compared. The transcriptome data of patients with SLE and age- and sex-matched HCs were obtained from ImmuNexUT. The expression of ENPP2, the gene encoding autotaxin, was examined in peripheral blood immune cells. Next, weighted gene correlation network analysis (WGCNA) was performed to identify genes with expression patterns similar to ENPP2. The ImmuNexUT eQTL database and public epigenomic databases were used to infer the relationship between autotaxin and pathogenesis of SLE. RESULTS: Autotaxin levels were elevated in the serum of patients with SLE compared to HCs. Furthermore, the expression of ENPP2 was higher in plasmacytoid dendritic cells (pDCs) than in other immune cell subsets, and its expression was elevated in pDCs of patients with SLE compared to HCs. In WGCNA, ENPP2 belonged to a module that correlated with disease activity. This module was enriched in interferon-associated genes and included genes whose expression was influenced by single-nucleotide polymorphisms associated with SLE, suggesting that it is a key module connecting genetic risk factors of SLE with disease pathogenesis. Analysis utilizing the ImmuNexUT eQTL database and public epigenomic databases suggested that the increased expression of ENPP2 in pDCs from patients with SLE may be caused by increased expression of interferon-associated genes and increased binding of STAT3 complexes to the regulatory region of ENPP2. CONCLUSIONS: Autotaxin may play a critical role in connecting genetic risk factors of SLE to disease pathogenesis in pDCs.

Identification of U11snRNA as an endogenous agonist of TLR7-mediated immune pathogenesis.

The activation of innate immune receptors by pathogen-associated molecular patterns (PAMPs) is central to host defense against infections. On the other hand, these receptors are also activated by immunogenic damage-associated molecular patterns (DAMPs), typically released from dying cells, and the activation can evoke chronic inflammatory or autoimmune disorders. One of the best known receptors involved in the immune pathogenesis is Toll-like receptor 7 (TLR7), which recognizes RNA with single-stranded structure. However, the causative DAMP RNA(s) in the pathogenesis has yet to be identified. Here, we first developed a chemical compound, termed KN69, that suppresses autoimmunity in several established mouse models. A subsequent search for KN69-binding partners led to the identification of U11 small nuclear RNA (U11snRNA) as a candidate DAMP RNA involved in TLR7-induced autoimmunity. We then showed that U11snRNA robustly activated the TLR7 pathway in vitro and induced arthritis disease in vivo. We also found a correlation between high serum level of U11snRNA and autoimmune diseases in human subjects and established mouse models. Finally, by revealing the structural basis for U11snRNA's ability to activate TLR7, we developed more potent TLR7 agonists and TLR7 antagonists, which may offer new therapeutic approaches for autoimmunity or other immune-driven diseases. Thus, our study has revealed a hitherto unknown immune function of U11snRNA, providing insight into TLR7-mediated autoimmunity and its potential for further therapeutic applications.

Egr2-independent, Klf1-mediated induction of PD-L1 in CD4+ T cells.

Programmed death ligand 1 (PD-L1)-mediated induction of immune tolerance has been vigorously investigated in autoimmunity and anti-tumor immunity. However, details of the mechanism by which PD-L1 is induced in CD4+ T cells are unknown. Here, we revealed the potential function of Klf1 and Egr2-mediated induction of PD-L1 in CD4+ T cells. We focused on the molecules specifically expressed in CD4+CD25-LAG3+ regulatory T cells (LAG3+ Tregs) highly express of PD-L1 and transcription factor Egr2. Although ectopic expression of Egr2 induced PD-L1, a deficiency of Egr2 did not affect its expression, indicating the involvement of another PD-L1 induction mechanism. Comprehensive gene expression analysis of LAG3+ Tregs and in silico binding predictions revealed that Krüppel-like factor 1 (Klf1) is a candidate inducer of the PD-L1 gene (Cd274). Klf1 is a transcription factor that promotes ß-globin synthesis in erythroid progenitors, and its role in immunological homeostasis is unknown. Ectopic expression of Klf1 induced PD-L1 in CD4+ T cells through activation of the PI3K-mTOR signaling pathway, independent of STATs signaling and Egr2 expression. Our findings indicate that Klf1 and Egr2 are modulators of PD-L1-mediated immune suppression in CD4+ T cells and might provide new insights into therapeutic targets for autoimmune diseases and malignancies.

Overview of LAG-3-Expressing, IL-10-Producing Regulatory T Cells.

Regulatory T cells (Treg cells) play crucial roles in the induction of peripheral tolerance to self- and foreign-antigens. IL-10-producing regulatory T cells (IL-10-producing Treg cells) constitute a Treg cell subset characterized by the production of high amounts of IL-10, cytokine-mediated immunosuppressive capabilities, and independence of Foxp3 expression for their suppressive activity. In the past decade, identifying naturally occurring IL-10-producing Treg cells was difficult due to the lack of suitable surface markers. More recently, lymphocyte activation gene 3 (LAG-3) is a CD4 homologue that has been identified as a marker for IL-10-producing Treg cells. CD4+CD25-LAG3+ T cells produce large amounts of IL-10 and suppress colitis in a mouse model. These CD4+CD25-LAG3+ Treg cells also exhibit suppressive activity in murine models of lupus and humoral immunity in a TGF-ß3-dependent manner. Moreover, the combined expression of LAG-3 and CD49b identifies IL-10-producing Treg cells in mice and humans more specifically. Recently, LAG-3 has gained more attention in the context of immune checkpoints because it believed to be related to T cell tolerance and exhausted T cells that infiltrate the tumor microenvironment. Tumors and the tumor microenvironment promote development of IL-10-producing Treg cells and foster tumor growth. This response might interfere with protective immune responses. Understanding LAG-3-expressing IL-10-producing Treg cells may contribute to the development of novel therapeutic strategies in immune-mediated diseases.

The metabolic regulation in immune cells and pathogenesis of systemic lupus erythematosus ∼toward new therapeutic applications∼.

The importance of cellular metabolism has long been known as Warburg effect; cancer cells are characterized by mitochondrial defect that shifts towards aerobic glycolysis. Recently, many reports have revealed that immune metabolism is a key factor for controlling immune cell proliferation and differentiation. Resting lymphocytes generate energy through oxidative phosphorylation and fatty acid oxidation, whereas activated lymphocytes rapidly shift to glycolysis. Especially in T cells, more precise mechanism of regulating metabolism have been clarified on differentiation from naïve T cells to effector T cells. Similar studies have also been carried out to characterize B cell and myeloid cell metabolism. Metabolic regulation is considered to be particularly important in autoimmune diseases. Metabolic changes in these diseases might not only reflect the chronic activated immune-status but also associated with their pathogenesis. Here, we review what is known on the altered metabolism in systemic lupus erythematosus (SLE), mainly focusing on T cells and B cells, and how they contribute to SLE pathogenesis. We also discuss how immune metabolic defects can become targets of future SLE therapy.

The effects of TGF-ßs on immune responses.

Transforming growth factor (TGF)-ß family is a cytokine family with various biological processes and forms a highly homologous group of three mammalian isoforms, TGF-ß1, TGF-ß2, and TGF-ß3. Most of the attention on TGF-ß family in immunology has been mainly focused on TGF-ß1 in that TGF-ß1 induces anti-inflammatory regulatory T cells (Treg), and inflammatory T helper 17 (Th17) cells in combination with interleukin-6. Although little attention has been focused on the immunological roles of TGF-ß2 and TGF-ß3, the function of TGF-ß3 for maintaining immunological homeostasis has recently been identified such as the induction of Th17 cells and direct regulatory effects on humoral immunity. TGF-ß1 and TGF-ß3 shares similar anti-inflammatory or pro-inflammatory functions, but exhibits significantly different effects on fibrosis and chondrogenesis. For the clinical application of TGF-ßs, the mechanisms by which each TGF-ß isoform regulates immunity has to be elucidated. In this review, we provide an overview of the effects, cellular targets, and therapeutic potential of TGF-ßs on immune responses and autoimmune diseases.

Role of TGF-ß3 in the regulation of immune responses.

Transforming growth factor-betas (TGF-ßs) are multifunctional cytokines that have been implicated in the regulation of a broad range of biological processes, including cell proliferation, cell survival, and cell differentiation. The three isoforms identified in mammals, TGF-ß1, TGF-ß2, and TGF-ß3, have high sequence homology, bind to the same receptors, and show similar biological functions in many in vitro studies. However, analysis of the in vivo functions of the three isoforms and mice deficient for each cytokine reveals striking differences, illustrating their unique biological importance and functional non-redundancy. Although increasing evidence suggests that TGF-ß1 and, to a lesser extent, TGF-ß2 play an integral role in maintaining immune tolerance, the immunological role of TGF-ß3 has not been carefully evaluated. Recent studies have focused on the multifunctional role of TGF-ß3. In this review, we provide an overview of the role of TGF-ß3 in immunity, with comparison to TGF-ß1 and -ß2.

A new T-cell activation mode for suboptimal doses of antigen under the full activation of T cells with different specificity.

Loss of tolerance for autoantigens is a common feature in autoimmune diseases. Bystander T-cell activation is the activation of T cells to produce functional changes through TCR-independent stimulation. Although bystander activation may be related to tolerance loss to multiple autoantigens, the activation mechanism of T cells directed to an autoantigen with limited amount is not clear. We investigated an activation mode of T cells (designated as "associator T cells") directed to a suboptimal dose of cognate antigen X in the presence of fully activated T cells (designated as "responder T cells") directed to an optimal dose of antigen Y. In in vitro coculture, the activation of associator T cells was dependent on the presentation of antigen X, and soluble factors from activated responder T cells were not sufficient. Therefore, we conclude this activation mode is different from bystander activation and named it "extended antigen priming (EAP)". T cells with EAP showed a different phenotype compared to conventionally primed cells, suggesting the unique nature of EAP. Intriguingly, EAP was dependent on the CD40-CD40L signaling pathway. Thus, the EAP model is a T-cell activation mode for suboptimal dose of antigen and presumably related to the immune response to autoantigens in autoimmune status.

Interleukin-27 in T cell immunity.

Interleukin (IL)-27, a member of IL-12/IL-23 heterodimeric family of cytokines, has pleiotropic properties that can enhance or limit immune responses. IL-27 acts on various cell types, including T cells, B cells, macrophages, dendritic cells, natural killer (NK) cells and non-hematopoietic cells. Intensive studies have been conducted especially on T cells, revealing that various subsets of T cells respond uniquely to IL-27. IL-27 induces expansion of Th1 cells by activating signal transducer and activator of transcription (STAT) 1-mediated T-bet signaling pathway. On the other hand, IL-27 suppresses immune responses through inhibition of the development of T helper (Th) 17 cells and induction of IL-10 production in a STAT1- and STAT3-dependent manner. IL-27 is a potentially promising cytokine for therapeutic approaches on various human diseases. Here, we provide an overview of the biology of IL-27 related to T cell subsets, its structure, and production mechanism.

Autoantibody against WD repeat domain 1 is a novel serological biomarker for screening of thyroid neoplasia.

BACKGROUND: Thyroid nodules are common among adults, and accurate diagnosis is critical in for management decisions. Ultrasound and fine needle aspiration cytology are the most common methods to evaluate nodules, but they are not practical for screening large numbers of patients because of cost and time considerations. OBJECTIVE: The aim of this study was to isolate an autoantibody to tumour antigen, WD repeat domain 1 (WDR1), and evaluate its diagnostic sensitivity and specificity for thyroid neoplasms. PATIENTS AND METHODS: We investigated serological biomarkers in patients with thyroid carcinoma who had a poor prognosis. Using a serological analysis of recombinant cDNA expression cloning (SEREX) strategy, we isolated WDR1 and its specific autoantibody in the sera of patients with undifferentiated thyroid carcinoma (UTC). We examined using indirect ELISA, the titre of the anti-WDR1 antibody (AWA) in 54 study patients: 10 with UTC, 20 with papillary thyroid carcinoma (PTC), 17 with benign thyroid nodule (BTN), 7 with autoimmune thyroid disease (AITD), as well as 38 controls (N). RESULTS: WDR1 was ubiquitously expressed in various types of thyroid tissues. However, the titre of AWA in UTC and PTC was significantly higher than that in BTN, AITD and N (P < 0·001). No significant correlation was observed between thyroid function, serum thyroglobulin and tumour diameter. The cut-off value estimated using ROC to differentiate malignancies from others was 0·95 (sensitivity 96·7%, specificity 91·9%, AUC 0·969, P < 0·001). CONCLUSIONS: Anti-WDR1 antibody could be a novel approach for serological screening of PTC and UTC, and could be an efficient and inexpensive biomarker.

CD4+CD25-LAG3+ regulatory T cells controlled by the transcription factor Egr-2.

Regulatory T cells (Tregs) are engaged in the maintenance of immunological self-tolerance and immune homeostasis. IL-10 has an important role in maintaining the normal immune state. Here, we show that IL-10-secreting Tregs can be delineated in normal mice as CD4(+)CD25(-)Foxp3(-) T cells that express lymphocyte activation gene 3 (LAG-3), an MHC-class-II-binding CD4 homolog. Although approximately 2% of the CD4(+)CD25(-) T cell population consisted of CD4(+)CD25(-)LAG3(+) T cells in the spleen, CD4(+)CD25(-)LAG3(+) T cells are enriched to approximately 8% in the Peyer's patch. They are hypoproliferative upon in vitro antigenic stimulation and suppress in vivo development of colitis. Gene expression analysis reveals that CD4(+)CD25(-)LAG3(+) Tregs characteristically express early growth response gene 2 (Egr-2), a key molecule for anergy induction. Retroviral gene transfer of Egr-2 converts naïve CD4(+) T cells into the IL-10-secreting and LAG-3-expressing phenotype, and Egr-2-transduced CD4(+) T cells exhibit antigen-specific immunosuppressive capacity in vivo. Unlike Foxp3(+) natural Tregs, high-affinity interactions with selecting peptide/MHC ligands expressed in the thymus do not induce the development of CD4(+)CD25(-)LAG3(+) Tregs. In contrast, the number of CD4(+)CD25(-)LAG3(+) Tregs is influenced by the presence of environmental microbiota. Thus, IL-10-secreting Egr-2(+)LAG3(+)CD4(+) Tregs can be exploited for the control of peripheral immunity.

Acute secondary gastrointestinal amyloidosis in a patient with rheumatoid arthritis.

Secondary amyloidosis is well recognized as a severe complication in the late stages of rheumatoid arthritis (RA). However, there have been few reported cases of secondary amyloidosis developing early during the course of RA. We here report the case of a 35-year-old woman, in whom RA who had been diagnosed 1 year before, with intractable watery diarrhea as a symptom of RA-induced secondary intestinal amyloidosis. Combination treatment with intravenous hyperalimentation, corticosteroids, and methotrexate (MTX) resulted in a dramatic improvement of her symptoms and objective findings of serological abnormalities. Subsequent administration of corticosteroids and MTX resulted in long-term survival without recurrence. This case indicates that we should be alert for the development of secondary amyloidosis, even in patients with a short history of RA, when the disease is active. Furthermore, combination therapy with intravenous hyperalimentation and strong immunosuppressive agents seems to be very efficacious in the treatment of RA-associated secondary intestinal amyloidosis.

Abnormally high expression of proteasome activator-gamma in thyroid neoplasm.

PA28-gamma is the activator of 20S proteasome, the ATP-dependent proteolytic system that plays an important role in cell cycle progression in various cell types. In this paper, we show the abnormally high expression of PA28-gamma in various thyroid neoplasms. Thyroid samples were obtained from patients with normal thyroid (4 cases) and with the following diseases: papillary adenocarcinoma (13 cases), multinodular goiter (4 cases), and anaplastic carcinoma (1 case). PA28-gamma expression was estimated by immunohistochemical staining and Western blotting. In all of the papillary adenocarcinoma samples, PA28-gamma was abnormally overexpressed, especially in cancer cells existing at the peripheral region of the cancer mass or in cancer cells invading the capsular region surrounding the cancer mass. In cancer cells of these areas, PA28-gamma was predominantly distributed in nucleus rather than in the cytoplasm of cancer cells. On the other hand, no obvious PA28-gamma expression was observed in the adjacent normal thyroid follicular cells. In multinodular goiter, the expression of PA28-gamma was relatively low compared with papillary adenocarcinoma. In anaplastic carcinoma, PA28-gamma was expressed at the highest level, especially in poorly differentiated regions such as squamous metaplasia of anaplastic cancer tissue. Therefore, the PA28-gamma expression seems to be restricted to thyroid cancer cells, especially in the region where the growth rate of cancer cells is accelerated. This result is further confirmed by the fact that C2, alpha-subunit of 20S proteasome, and proliferating cell nuclear antigen are similarly overexpressed in this region. Thus, PA28-gamma might be involved in the regulatory system for the cell cycle. Moreover, the growth of thyroid cancer cell lines was affected by the proteasome inhibitor, clasto-lactacystin beta-lactone. These results demonstrate that PA28-gamma is overexpressed in thyroid cancer, especially in its growth-accelerated cells.