IL-23 induces CLEC5A+ IL-17A+ neutrophils and elicit skin inflammation associated with psoriatic arthritis.

IL-23-activation of IL-17 producing T cells is involved in many rheumatic diseases. Herein, we investigate the role of IL-23 in the activation of myeloid cell subsets that contribute to skin inflammation in mice and man. IL-23 gene transfer in WT, IL-23RGFP reporter mice and subsequent analysis with spectral cytometry show that IL-23 regulates early innate immune events by inducing the expansion of a myeloid MDL1+CD11b+Ly6G+ population that dictates epidermal hyperplasia, acanthosis, and parakeratosis; hallmark pathologic features of psoriasis. Genetic ablation of MDL-1, a major PU.1 transcriptional target during myeloid differentiation exclusively expressed in myeloid cells, completely prevents IL-23-pathology. Moreover, we show that IL-23-induced myeloid subsets are also capable of producing IL-17A and IL-23R+MDL1+ cells are present in the involved skin of psoriasis patients and gene expression correlations between IL-23 and MDL-1 have been validated in multiple patient cohorts. Collectively, our data demonstrate a novel role of IL-23 in MDL-1-myelopoiesis that is responsible for skin inflammation and related pathologies. Our data open a new avenue of investigations regarding the role of IL-23 in the activation of myeloid immunoreceptors and their role in autoimmunity.

Early initiation of angiotensin-converting enzyme inhibitor in patients with scleroderma renal crisis: A nationwide inpatient database study.

OBJECTIVES: To evaluate the effectiveness of early initiation of angiotensin-converting enzyme inhibitor (ACEi) in patients with scleroderma renal crisis (SRC). METHODS: This was a retrospective cohort study using a nationwide inpatient database in Japan from July 2010 to March 2020. All hospitalized patients with SRC were divided into those who received ACEi within two days of admission (early ACEi group) and those who did not (control group). Propensity-score overlap weighting analysis was performed to adjust for confounding factors. The primary outcome was the composite of in-hospital mortality or hemodialysis dependence at discharge. RESULTS: Of the 475 eligible patients, 248 (52.2%) were in the early ACEi group and 227 (47.8%) were in the control group. After overlap weighting, the primary outcome was significantly lower in the early ACEi group than in the control group (40.1% vs. 49.0%; odds ratio, 0.69; 95% confidence interval, 0.48-1.00; P= 0.049). CONCLUSIONS: The present study showed that early initiation of ACEi was associated with lower composite outcome of in-hospital mortality or hemodialysis dependence at discharge in patients with SRC. Further prospective studies are warranted to verify the present findings.

Interleukin-23 Regulates Inflammatory Osteoclastogenesis via Activation of CLEC5A(+) Osteoclast Precursors.

OBJECTIVE: To investigate the role of interleukin-23 (IL-23) in pathologic bone remodeling in inflammatory arthritis. METHODS: In this study we investigated the role of IL-23 in osteoclast differentiation and activation using in vivo gene transfer techniques in wild-type and myeloid DNAX-activation protein 12-associating lectin-1 (MDL-1)-deficient mice, and by performing in vitro and in vivo osteoclastogenesis assays using spectral flow cytometry, micro-computed tomography analysis, Western blotting, and immunoprecipitation. RESULTS: Herein, we show that IL-23 induces the expansion of a myeloid osteoclast precursor population and supports osteoclastogenesis and bone resorption in inflammatory arthritis. Genetic ablation of C-type lectin domain family member 5A, also known as MDL-1, prevents the induction of osteoclast precursors by IL-23 that is associated with bone destruction, as commonly observed in inflammatory arthritis. Moreover, osteoclasts derived from the bone marrow of MDL-1-deficient mice showed impaired osteoclastogenesis, and MDL-1-/- mice had increased bone mineral density. CONCLUSION: Our data show that IL-23 signaling regulates the availability of osteoclast precursors in inflammatory arthritis that could be effectively targeted for the treatment of inflammatory bone loss in inflammatory arthritis.

Group 2 innate lymphoid cells in human asthma.

Asthma is characterized by increased airway hyperresponsiveness, reversible airflow limitation, and remodeling due to allergic airway inflammation. Asthma has been proposed to be classified into various phenotypes by cluster analyses integrating clinical information and laboratory data. Recently, asthma has been classified into two major endotypes, Type 2-high and Type 2-low asthma, and various subtypes based on the underlying molecular mechanisms. In Type 2-high asthma, Th2 cells, together with group 2 innate lymphoid cells (ILC2s), produce type 2 cytokines such as IL-4, IL-5, IL-9, and IL-13, which play crucial roles in causing airway inflammation. The roles of ILC2s in asthma pathogenesis have been analyzed primarily in murine models, demonstrating their importance not only in IL-33- or papain-induced innate asthma models but also in house dust mite (HDM)- or ovalbumin (OVA)-induced acquired asthma models evoked in an antigen-specific manner. Recently, evidence regarding the roles of ILC2s in human asthma is also accumulating. This minireview summarizes the roles of ILC2s in asthma, emphasizing human studies.

Peripheral γδ T Cells Regulate Neutrophil Expansion and Recruitment in Experimental Psoriatic Arthritis.

OBJECTIVE: This study was undertaken to identify the mechanistic role of γδ T cells in the pathogenesis of experimental psoriatic arthritis (PsA). METHODS: In this study, we performed interleukin-23 (IL-23) gene transfer in wild-type (WT) and T cell receptor δ-deficient (TCRδ-/- ) mice and conducted tissue phenotyping in the joint, skin, and nails to characterize the inflammatory infiltrate. We further performed detailed flow cytometry, immunofluorescence staining, RNA sequencing, T cell repertoire analysis, and in vitro T cell polarization assays to identify regulatory mechanisms of γδ T cells. RESULTS: We demonstrated that γδ T cells support systemic granulopoiesis, which is critical for murine PsA-like pathology. Briefly, γδ T cell ablation inhibited the expression of neutrophil chemokines CXCL1 and CXCL2 and neutrophil CD11b+Ly6G+ accumulation in the aforementioned PsA-related tissues. Although significantly reduced expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-17A was detected systemically in TCRδ-/- mice, no GM-CSF+/IL-17A+ γδ T cells were detected locally in the inflamed skin or bone marrow in WT mice. Our data showed that nonresident γδ T cells regulate the expansion of an CD11b+Ly6G+ neutrophil population and their recruitment to joint and skin tissues, where they develop hallmark pathologic features of human PsA. CONCLUSION: Our findings do not support the notion that tissue-resident γδ T cells initiate the disease but demonstrate a novel role of γδ T cells in neutrophil regulation that can be exploited therapeutically in PsA patients.

Prognosis and Treatment of Myositis-Associated Severe Interstitial Lung Disease: A Descriptive Study Using a Nationwide Inpatient Database in Japan.

OBJECTIVE: The aim of this study was to determine the prognosis, clinical course, and current management of severe interstitial lung disease (ILD) associated with myositis in Japan. METHODS: We conducted a retrospective descriptive study using a nationwide database for inpatient care of acute illness in Japan. Among a total of ~66 million inpatient admissions, we identified patients with severe ILD associated with polymyositis (PM) or dermatomyositis (DM) who required mechanical ventilation and methylprednisolone pulse therapy (≥1 gm/day of methylprednisolone) from July 2010 to March 2018. RESULTS: We identified 155 patients with PM and 394 with DM who fulfilled the above criteria. The median age of patients was 65 years; DM patients were significantly younger than PM patients (64 versus 68 years; P < 0.001). The numbers of patients who were treated with calcineurin inhibitors, intravenous cyclophosphamide, and polymyxin B-immobilized fiber column direct hemoperfusion (PMX-DHP) were 403 (73.4%), 318 (57.9%), and 78 (14.2%), respectively. All these treatments were given significantly more frequently to the patients with DM compared with those with PM. The uses of other treatment options were much less frequent. The median periods after hospitalization when methylprednisolone pulse therapy, calcineurin inhibitors, mechanical ventilation, intravenous cyclophosphamide, and PMX-DHP were initiated and in-hospital death occurred among patients with DM were 2, 4, 7, 8, 17, and 36 days, respectively. In-hospital mortality was significantly higher in patients with DM than in those with PM (76.6% versus 56.8%; P < 0.001). CONCLUSION: The mortality of patients with myositis-associated severe ILD who require mechanical ventilation is extremely high despite aggressive and prompt interventions.

Intravenous cyclophosphamide in acute exacerbation of rheumatoid arthritis-related interstitial lung disease: A propensity-matched analysis using a nationwide inpatient database.

OBJECTIVES: We aimed to investigate the effect of intravenous cyclophosphamide (CYC) as the initial therapy in patients with acute exacerbation of rheumatoid arthritis-related interstitial lung disease. METHODS: This was a retrospective observational study. Using the Japanese Diagnosis Procedure Combination inpatient database from July 2010 to March 2018, we identified patients with acute exacerbation of rheumatoid arthritis-related interstitial lung disease (RA-ILD) who received high-dose methylprednisolone within 3 days after admission. RA-ILD was defined as having either the diagnosis of RA-ILD or the diagnoses of both RA and ILD, based on the ICD-10 codes recorded by attending physicians. Patients were divided into two groups: those receiving intravenous CYC within 3 days after admission (CYC group) and those who did not (control group). One-to-four propensity-score matching analyses were performed. RESULTS: A total of 6130 eligible patients were included. After propensity score matching, 129 patients in the CYC group and 516 patients in the control group were further analyzed. 90-day in-hospital mortality, defined as all-cause mortality during hospitalization within 90 days after admission, was not significantly different between the CYC and control groups (50.4% versus 42.2%, hazard ratio 1.20, 95% confidence interval 0.91-1.58). A larger proportion of patients in the CYC group received platelet transfusion than that in the control group (7.0% versus 2.3%, odds ratio 3.05, 95% confidence interval 1.20-7.73). CONCLUSION: In this retrospective database study, the initial therapy with CYC did not show a survival benefit in patients with acute exacerbation of RA-ILD. CYC was associated with a larger proportion of platelet transfusion.

Associations of ultrasound-based inflammation patterns with peripheral innate lymphoid cell populations, serum cytokines/chemokines, and treatment response to methotrexate in rheumatoid arthritis and spondyloarthritis.

OBJECTIVES: We aimed to explore the associations of musculoskeletal inflammation patterns with peripheral blood innate lymphoid cell (ILC) populations, serum cytokines/chemokines, and treatment response to methotrexate in patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA). METHODS: We enrolled 100 patients with either RA or SpA and performed ultrasound to evaluate power Doppler signals for synovitis (52 joint regions), tenosynovitis (20 tendons), and enthesitis (44 sites). We performed clustering analysis using unsupervised random forest based on the multi-axis ultrasound information and classified the patients into groups. We identified and counted ILC1-3 populations in the peripheral blood by flow cytometry and also measured the serum levels of 20 cytokines/chemokines. We also determined ACR20 response at 3 months in 38 patients who began treatment with methotrexate after study assessment. RESULTS: Synovitis was more prevalent and severe in RA than in SpA, whereas tenosynovitis and enthesitis were comparable between RA and SpA. Patients were classified into two groups which represented synovitis-dominant and synovitis-nondominant inflammation patterns. While peripheral ILC counts were not significantly different between RA and SpA, they were significantly higher in the synovitis-nondominant group than in the synovitis-dominant group (ILC1-3: p = 0.0007, p = 0.0061, and p = 0.0002, respectively). On the other hand, clustering of patients based on serum cytokines/chemokines did not clearly correspond either to clinical diagnoses or to synovitis-dominant/nondominant patterns. The synovitis-dominant pattern was the most significant factor that predicted clinical response to methotrexate (p = 0.0065). CONCLUSIONS: Musculoskeletal inflammation patterns determined by ultrasound are associated with peripheral ILC counts and could predict treatment response to methotrexate.

Sox12 enhances Fbw7-mediated ubiquitination and degradation of GATA3 in Th2 cells.

Allergic asthma that is caused by inhalation of house dust mites (HDMs) is mainly mediated by Th2 cells. Recently, the roles of Sox (SRY-related high-mobility-group (HMG)-box) family members in various immune responses have been investigated. However, the roles of Sox12, a member of the SoxC group, in Th2 cell differentiation and allergic airway inflammation, remain unknown. We showed that Sox12 mRNA was significantly increased during Th2 cell differentiation. In vivo, HDM-induced eosinophil infiltration into the lung and Th2 cell differentiation were exacerbated in Sox12-/- mice compared with those in control Sox12+/- mice. In vitro, Sox12-/- CD4+ T cells that were cultured under Th2 conditions had increased production of Th2 cytokines and GATA3 protein compared with those of control Sox12+/- CD4+ T cells. Importantly, forced expression of Sox12 decreased the protein levels of GATA3 in CD4+ T cells under Th2 conditions without affecting mRNA expression. Furthermore, Sox12 induced degradation of GATA3 through the proteasome pathway in CD4+ T cells. Consistently, Sox12 enhanced ubiquitination of GATA3, which was mediated by the E3 ligase Fbw7. Finally, we found that Fbw7 knockdown partly abrogated Sox12-mediated GATA3 suppression in CD4+ T cells. Taken together, these results suggest that Sox12 suppresses Th2 cell differentiation by accelerating Fbw7-mediated GATA3 degradation, and attenuates HDM-induced allergic inflammation.

Efficacy of rituximab for anti-neutrophil cytoplasmic antibody-associated hypertrophic pachymeningitis: a case series.

OBJECTIVES: This study researched the efficacy of rituximab (RTX) in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated hypertrophic pachymeningitis (HP). METHODS: Eight patients were identified by retrospective chart review from local registries at four hospitals in Japan. All patients met the Chapel Hill 2012 Consensus Conference definitions of ANCA-associated vasculitis and had disease complicated with HP. We assessed the dose of glucocorticoids, C-reactive protein (CRP) levels, Birmingham vasculitis activity score (BVAS) and contrast-enhanced magnetic resonance imaging (MRI) findings of HP before and after RTX administration. RESULTS: Three of eight patients were female. The median age was 68 years. No patients had HP at onset of vasculitis. Two patients had a relapse of HP before RTX administration. RTX was used as the initial treatment for HP in three patient. The daily dose of glucocorticoids, CRP levels and BVAS decreased from baseline to 6 months after RTX treatment in all patients. Evaluation of HP by contrast-enhanced MRI showed improvement in seven of eight cases. All of seven patients achieved sustained remission at 6 months after RTX treatment. No serious adverse events were observed in any patient. CONCLUSIONS: Our case series highlights the efficacy of RTX in patients with difficult-to-treat ANCA-associated HP. Future prospective studies are warranted to establish B-cell depletion therapy by RTX as a treatment option for ANCA-associated HP.

Experience of musculoskeletal ultrasound scanning improves physicians' physical examination skills in assessment of synovitis.

OBJECTIVE: Musculoskeletal ultrasound (US) is more sensitive than physical examination in detecting synovitis and helps physicians to understand its pathophysiology. In this study, we aimed to determine if the experience in musculoskeletal US scanning is independently associated with improved physical examination skills to detect synovitis. METHOD: Seventy patients with rheumatoid arthritis and twenty-three physicians were enrolled. Patients were first assessed by multiple physicians with a range of clinical/sonographic experience for the swelling of the wrist, metacarpophalangeal and proximal interphalangeal (PIP) joints and next underwent US assessment performed by another physician experienced in musculoskeletal US. We then calculated the positive/negative predictive values (PPV/NPV) of joint swelling to identify US-detected synovial hypertrophy. Finally, the factors independently associated with the accuracy of clinical assessment were identified by using multivariate analyses. RESULTS: One thousand five hundred forty joints were assessed 6116 times in total for swelling. Overall, PPV and NPV of joint swelling were 51.7% and 88.3%, respectively. Multivariate analyses identified wrist joint, tenderness, male and greater patients' age as the factors significantly associated with higher PPV. In addition, there was a trend that longer experience in rheumatology clinical practice was associated with higher PPV (p = 0.058). On the other hand, longer experience in musculoskeletal US, PIP joint and positive rheumatoid factor were identified as the significant factors for higher NPV, while wrist joint, tenderness, presence of osteophyte and obesity as those for lower NPV. CONCLUSION: Our data suggest that the experience in musculoskeletal US improves physical examination skills particularly to avoid overestimation.Key Points• Physicians with longer US experience are less likely to overestimate synovitis by physical examination.• Musculoskeletal US is a useful tool for rheumatologists to improve their physical examination skill.• Presence of osteophytes, joint tenderness and obesity influence the accuracy of physical examination of joints.