A case of refractory systemic lupus erythematosus with monocytosis exhibiting somatic KRAS mutation

BACKGROUND: Systemic lupus erythematosus (SLE), an autoimmune disorder that damages various organ systems, is caused by a combination of genetic and environmental factors. Although germline mutations of several genes are known to cause juvenile SLE, most of the susceptibility genetic variants of adult SLE are common variants of the population, somatic mutations that cause or exacerbate SLE have not been reported. We hereby report a refractory SLE case with monocytosis accompanying somatic KRAS mutation that have been shown to cause lupus-like symptoms. CASE PRESENTATION: A 60-year-old female patient who had been diagnosed with SLE was admitted to our hospital. Although prednisolone and tacrolimus treatments had kept her thrombocytopenia and anti-DNA Ab level at bay for more than 4 years, a diagnosis of transverse myelitis was made when she became acutely ill with pleocytosis. Elevated cells (predominately monocytes), protein, IgG, and IL-6 levels were also found in the cerebrospinal fluid (CSF) of the patient. Standard pulse treatments of methylprednisolone, high-dose of prednisolone, and intravenous cyclophosphamide in combination with plasma exchange could not alleviate the refractory neural and autoimmune manifestation. Monocytosis of peripheral blood was also noted. Flow cytometric analysis revealed elevated ratio of CD14+CD16+ atypical monocytes, which excluded the possibility of chronic myelomonocytic leukemia. Lupus-like symptoms with monocytosis reminded us of Ras-associated autoimmune leukoproliferative disorder, and Sanger sequencing of KRAS and NRAS genes from the patients' peripheral blood mononuclear cells (PBMC), sorted CD3+ lymphocytes and CD14+ monocytes, and cerebrospinal fluid were performed. An activating KRAS somatic mutation was found in the patients' DNA at the time of encephalomyelitis diagnosis. CONCLUSION: Somatic mutations of some genes including KRAS may cause the refractoriness of SLE

Positive and negative regulation of the Fcγ receptor–stimulating activity of RNA-containing immune complexes by RNase

The U1RNP complex, Ro/SSA, and La/SSB are major RNA-containing autoantigens. Immune complexes (ICs) composed of RNA-containing autoantigens and autoantibodies are suspected to be involved in the pathogenesis of some systemic autoimmune diseases. Therefore, RNase treatment, which degrades RNA in ICs, has been tested in clinical trials as a potential therapeutic agent. However, no studies to our knowledge have specifically evaluated the effect of RNase treatment on the Fcγ receptor–stimulating (FcγR-stimulating) activity of RNA-containing ICs. In this study, using a reporter system that specifically detects FcγR-stimulating capacity, we investigated the effect of RNase treatment on the FcγR-stimulating activity of RNA-containing ICs composed of autoantigens and autoantibodies from patients with systemic autoimmune diseases such as systemic lupus erythematosus. We found that RNase enhanced the FcγR-stimulating activity of Ro/SSA- and La/SSB-containing ICs, but attenuated that of the U1RNP complex–containing ICs. RNase decreased autoantibody binding to the U1RNP complex, but increased autoantibody binding to Ro/SSA and La/SSB. Our results suggest that RNase enhances FcγR activation by promoting the formation of ICs containing Ro/SSA or La/SSB. Our study provides insights into the pathophysiology of autoimmune diseases involving anti-Ro/SSA and anti-La/SSB autoantibodies, and into the therapeutic application of RNase treatment for systemic autoimmune diseases.Naito R., Ohmura K., Higuchi S., et al. Positive and negative regulation of the Fcγ receptor–stimulating activity of RNA-containing immune complexes by RNase. JCI Insight 8, e167799 (2023); https://doi.org/10.1172/jci.insight.167799

Attenuation of HOIL-1L ligase activity promotes systemic autoimmune disorders by augmenting linear ubiquitin signaling

自己免疫疾患の発症メカニズムの一端を解明 --自己免疫疾患の新規治療ターゲットへ--. 京都大学プレスリリース. 2024-02-09.Linear ubiquitin chains, which are generated specifically by the linear ubiquitin assembly complex (LUBAC) ubiquitin ligase, play crucial roles in immune signaling, including NF-κB activation. LUBAC comprises catalytic large isoform of heme-oxidized iron regulatory protein 2 ubiquitin ligase 1 (HOIL-1L) interacting protein (HOIP), accessory HOIL-1L, and SHANK-associated RH domain-interacting protein (SHARPIN). Deletion of the ubiquitin ligase activity of HOIL-1L, an accessory ligase of LUBAC, augments LUBAC functions by enhancing LUBAC-mediated linear ubiquitination, which is catalyzed by HOIP. Here, we show that HOIL-1L ΔRING1 mice, which exhibit augmented LUBAC functions upon loss of the HOIL-1L ligase, developed systemic lupus erythematosus (SLE) and Sjögren's syndrome in a female-dominant fashion. Augmented LUBAC activity led to hyperactivation of both lymphoid and myeloid cells. In line with the findings in mice, we sought to identify missense single nucleotide polymorphisms/variations of the RBCK1/HOIL-1L gene in humans that attenuate HOIL-1L ligase activity. We found that the R464H variant, which is encoded by rs774507518 within the RBCK1/HOIL-1L gene, attenuated HOIL-1L ligase activity and augmented LUBAC-mediated immune signaling, including that mediated by Toll-like receptors. We also found that rs774507518 was enriched significantly in patients with SLE, strongly suggesting that RBCK1/HOIL-1L is an SLE susceptibility gene and that augmented linear ubiquitin signaling generated specifically by LUBAC underlies the pathogenesis of this prototype systemic autoimmune disease

Increased number of T cells and exacerbated inflammatory pathophysiology in a human IgG4 knock-in MRL/lpr mouse model

Immunoglobulin (Ig) G4 is an IgG subclass that can exhibit inhibitory functions under certain conditions because of its capacity to carry out Fab-arm exchange, inability to form immune complexes, and lack of antibody-dependent and complement-dependent cytotoxicity. Although several diseases have been associated with IgG4, its role in the disease pathogeneses remains unclear. Since mice do not express an IgG subclass that is identical to the human IgG4 (hIgG4), we generated hIGHG4 knock-in (KI) mice and analyzed their phenotypes. To preserve the rearrangement of the variable, diversity, and joining regions in the IGH gene, we transfected a constant region of the hIGHG4 gene into C57BL/6NCrSlc mice by using a gene targeting method. Although the mRNA expression of hIGHG4 was detected in the murine spleen, the serum level of the hIgG4 protein was low in C57BL/6-IgG4KI mice. To enhance the production of IgG4, we established an MRL/lpr-IgG4KI mice model by backcrossing. These mice showed a high IgG4 concentration in the sera and increased populations of IgG4-positive plasma cells and CD3+B220+CD138+ T cells in the spleen. Moreover, these mice showed aggravated inflammation in organs, such as the salivary glands and stomach. The MRL/lpr-IgG4KI mouse model established in the present study might be useful for studying IgG4-related disease, IgG4-type antibody-related diseases, and allergic diseases

Medium-term impact of the SARS-CoV-2 mRNA vaccine against disease activity in patients with systemic lupus erythematosus

全身性エリテマトーデスへのコロナワクチンの影響を分析 --中期的な疾患活動性と再燃への影響について--. 京都大学プレスリリース. 2022-10-25.OBJECTIVES: Numerous case reports have referred to new onset or flare of SLE after SARS-CoV-2 messenger RNA (mRNA) vaccines. Several observational studies showed that the short-term flare rate of SLE after SARS-CoV-2 vaccination is low. However, well-controlled clinical surveys are unavailable and the medium-term impact of the SARS-CoV-2 mRNA vaccines against the flare of SLE is uncertain. Therefore, we aimed to analyse the association between vaccination and medium-term subjective and objective disease activities of SLE and flares using matched pair methods. METHODS: Altogether, 150 patients with SLE from the Kyoto Lupus Cohort were included. Patients who received two doses of the SARS-CoV-2 mRNA vaccines were 1:1 matched with unvaccinated patients based on the first vaccination date. The outcome measures were the SLE Disease Activity Index-2000 (SLEDAI-2K), the Japanese version of the SLE Symptom Checklist Questionnaire (SSC-J) and the Safety of Estrogens in Lupus Erythematosus National Assessment-SLEDAI flare index at 30, 60 and 90 days after vaccination. RESULTS: SLEDAI-2K levels were not significantly different in vaccinated and unvaccinated patients with SLE at 30, 60 and 90 days after the second vaccination (adjusted estimate (95% CI): 30 days: -0.46 (-1.48 to 0.56), p=0.39; 60 days: 0.38 (-0.64 to 1.40), p=0.47; 90 days: 0.40 (-0.54 to 1.34), p=0.41). Similar results were observed in the SSC-J score (adjusted estimate (95% CI), 30 days: 0.05 (-1.46 to 1.56), p=0.95; 60 days: -0.63 (-2.08 to 0.82), p=0.40; 90 days: 0.27 (-1.04 to 1.58), p=0.69) and flare index (adjusted OR (95% CI), 30 days: 0.81 (0.36 to 1.85), p=0.62; 60 days: 1.13 (0.50 to 2.54), p=0.77; 90 days: 0.85 (0.32 to 2.26), p=0.74). CONCLUSION: SARS-CoV-2 vaccination did not significantly influence the medium-term subjective and objective disease activities or flares of SLE until 90 days after the second vaccination

Phenotypic landscape of systemic lupus erythematosus: An analysis of the Kyoto Lupus Cohort

Objectives: The present study aimed to clarify comprehensive relationships among the clinical variables of systemic lupus erythematosus (SLE). Methods: We retrospectively surveyed 32 clinical variables in 581 patients and conducted comprehensive association studies among SLE clinical phenotypes. A univariate analysis of all possible combinations was performed, and the results of phenotypic correlations were reduced into two dimensions. We also created a regression formula using L1 regularisation (LASSO) to calculate the probability of exhibiting each phenotype. Results: The univariate analysis identified 26 correlations, including multiple phenotypes with low complement. Some unpredicted correlations were identified, including fever and the anti-Sm antibody (odds ratio; OR = 2.3, p = 1.6 × 10⁻⁵) or thrombocytopenia and psychosis (OR = 3.7, p = 3.2 × 10⁻⁵). The multivariate analysis accurately estimated the probability of exhibiting each phenotype (area under the curve > 0.7) in 10 out of 20 phenotypes. Conclusions: The present results show the phenotypic architecture of SLE and represent a model for estimating the probability of exhibiting each phenotype. They also offer insights into the pathology of SLE and estimating the probability of the onset of new phenotypes in clinical practice

The clinical features of pulmonary artery involvement in Takayasu arteritis and its relationship with ischemic heart diseases and infection

BACKGROUND: Pulmonary artery involvement (PAI) in Takayasu arteritis (TAK) can lead to severe complications, but the relationship between the two has not been fully clarified. METHODS: We retrospectively investigated 166 consecutive patients with TAK who attended Kyoto University Hospital from 1997 to 2018. The demographic data, clinical symptoms and signs, comorbidities, treatments, and imaging findings were compared between patients with and without PAI. TAK was diagnosed based on the American College of Rheumatology Classification Criteria (1990) or the Japanese Clinical Diagnostic Criteria (2008). PAI was identified using enhanced computed tomography, magnetic resonance imaging, or lung scintigraphy. RESULTS: PAI was detected in 14.6% (n = 24) of total TAK patients. Dyspnea (25.0% vs. 8.6%; p = 0.043), pulmonary arterial hypertension (PAH) (16.7% vs. 0.0%; p < 0.001), ischemic heart disease (IHD) (29% vs. 9.3%; p = 0.018), respiratory infection (25.0% vs. 6.0%; p = 0.009), and nontuberculous mycobacteria (NTM) infection (20.8% vs. 0.8%; p < 0.001) were significantly more frequent, and renal artery stenosis (0% vs. 17%; p = 0.007) was significantly less frequent in TAK patients with PAI than in those without PAI. PAI and biologics were risk factors for NTM. CONCLUSIONS: TAK patients with PAI more frequently have dyspnea, PAH, IHD, and respiratory infection, including NTM, than TAK patients without PAI

Oral dextran sulfate sodium administration induces peripheral spondyloarthritis features in SKG mice accompanied by intestinal bacterial translocation and systemic Th1 and Th17 cell activation

BACKGROUND: Spondyloarthritis (SpA) is an autoimmune and autoinflammatory musculoskeletal disease characterised by systemic enthesitis. Recent research has focused on subclinical inflammatory bowel disease (IBD) in SpA pathogenesis. SKG mice, harbouring the Zap70 W163C mutation, increase autoreactive Th17 cells intrinsically, and in a conventional environment, they exhibit spontaneous arthritis with fungal factors. Under SPF conditions, they show SpA features, including enteritis, after peritoneal injection of β-1, 3-glucan. This study aimed to clarify whether oral dextran sulfate sodium (DSS) administration, utilised in IBD model mice, can provoke SpA features in SKG mice under SPF conditions, focusing on the relationship between gut microorganisms and SpA pathogenesis. METHODS: BALB/c and SKG mice were administered oral DSS, and their body weights, arthritis, and enthesitis scores were recorded. In another cohort, antibiotics (meropenem and vancomycin) or an anti-fungal agent (amphotericin B) was administered orally before DSS administration. The splenic Th1 and Th17 cell populations were examined before and after DSS administration using flow cytometry. Furthermore, the amount of circulating bacterial DNA in whole blood was measured by absolute quantitative polymerase chain reaction (qPCR), and the number and characteristics of bacterial species corresponding to these circulating DNA were analysed by next-generation sequencing (NGS). RESULTS: Ankle enthesitis as a peripheral SpA feature was elicited in half of DSS-administered SKG mice, and none of the BALB/c mice. Pre-administration of antibiotics suppressed enthesitis, whilst an anti-fungal agent could not. Th1 and Th17 cell levels in the spleen increased after DSS administration, and this was suppressed by pre-administration of antibiotics. SKG mice have a larger amount of bacterial DNA in whole blood than BALB/c mice before and 1 day after the initiation of DSS administration. The number of bacterial species in whole blood increased after DSS administration in BALB/c and SKG mice. Some genera and species significantly specific to the DSS-treated SKG mouse group were also detected. CONCLUSION: Oral DSS administration alone elicited peripheral enthesitis in SKG mice with bacterial translocation accompanied by increased splenic Th1 and Th17 cell levels. Pre-administration of antibiotics ameliorated these DSS-induced SpA features. These findings suggest that intestinal bacterial leakage plays a pivotal role in SpA pathogenesis

Non-drug and surgical treatment algorithm and recommendations for the 2020 update of the Japan College of Rheumatology clinical practice guidelines for the management of rheumatoid arthritis—secondary publication

[Objectives] The aim of this study was to update the Japan College of Rheumatology (JCR) clinical practice guidelines (CPGs) for the management of rheumatoid arthritis (RA) and prepare an algorithm for non-drug and surgical treatments. This article is a digest version of the guidelines. [Methods] The Japanese Ministry of Health, Labour and Welfare’s research group, in collaboration with the JCR, used the Grading of Recommendations, Assessment, Development, and Evaluation method to update the 2014 JCR CPG for RA. The consensus was formed by CPG panel members. [Results] We raised 19 clinical questions regarding non-drug and surgical treatments for RA and developed recommendations. The treatments included exercise therapy; occupational therapy; joint injection of corticosteroids; and orthopaedic surgeries including cervical spine surgery, wrist and foot arthroplasty, ankle arthrodesis, and replacement arthroplasty of the shoulder, elbow, finger, hip, knee, and ankle. Recommendations regarding the risks of surgery and perioperative discontinuation of medications have also been developed. Based on these recommendations, we created an original algorithm for the non-drug and surgical treatment of RA. [Conclusions] These recommendations are expected to serve rheumatologists, health care professionals, and patients with RA as tools for shared decision-making to treat residual limb joint symptoms and functional impairment