Immune mechanisms in fibrotic interstitial lung disease.

Fibrotic interstitial lung diseases (fILDs) have poor survival rates and lack effective therapies. Despite evidence for immune mechanisms in lung fibrosis, immunotherapies have been unsuccessful for major types of fILD. Here, we review immunological mechanisms in lung fibrosis that have the potential to impact clinical practice. We first examine innate immunity, which is broadly involved across fILD subtypes. We illustrate how innate immunity in fILD involves a complex interplay of multiple cell subpopulations and molecular pathways. We then review the growing evidence for adaptive immunity in lung fibrosis to provoke a re-examination of its role in clinical fILD. We close with future directions to address key knowledge gaps in fILD pathobiology: (1) longitudinal studies emphasizing early-stage clinical disease, (2) immune mechanisms of acute exacerbations, and (3) next-generation immunophenotyping integrating spatial, genetic, and single-cell approaches. Advances in these areas are essential for the future of precision medicine and immunotherapy in fILD.

Effectiveness and safety of treat-to-target strategy for methotrexate-naïve rheumatoid arthritis patients >75 years of age.

Objectives: To identify differences in effectiveness and safety of a treat-to-target (T2T) strategy comparing late-onset MTX-naïve RA patients (LORA) ≥75 or <75 years of age. Methods: Treatment was adjusted to target low disease activity with conventional synthetic DMARDs followed by biologic DMARDs (bDMARDs) in LORA ≥75 years (n = 98, mean age 80.0 years) and LORA <75 years (n = 99) with moderate-high disease activity. Achievement of Simplified Disease Activity Index (SDAI) remission at week 156 by non-responder imputation analysis was evaluated as a primary outcome. Results: LORA ≥75 years had more comorbidities than LORA <75 years, but SDAI and ACPA positivity were similar at baseline. Of the LORA ≥75 years, 70.4% started MTX and 34.1% and 37.1% received a bDMARD at week 52 and 156, respectively (very similar to the LORA <75 years). Glucocorticoid use was more frequent in the LORA ≥75 years than in the LORA <75 years. Comorbidities/adverse events more frequently contributed to the reasons for non-adherence to T2T in the LORA ≥75 than in the LORA <75. At week 156, 32.7% of the LORA ≥75 and 66.7% of the LORA <75 achieved SDAI remission (P < 0.001). The cumulative incidence of serious adverse events (SAEs) over 156 weeks was 42.8% in the LORA ≥75 and 22.1% in the LORA <75. Multivariable analysis indicated an increased risk of SDAI non-remission at week 156 in the LORA ≥75 [odds ratio 2.82 (95% CI 1.29. 6.14)] after adjusting for comorbidities at baseline, non-adherence to T2T and SAEs. Conclusions: It was more difficult to achieve remission in the LORA ≥75 patients than in the LORA <75 patients due to both poor treatment response and safety issues.

Activation of CD8+ T Cells in Chronic Obstructive Pulmonary Disease Lung.

Rationale: Despite the importance of inflammation in chronic obstructive pulmonary disease (COPD), the immune cell landscape in the lung tissue of patients with mild-moderate disease has not been well characterized at the single-cell and molecular level. Objectives: To define the immune cell landscape in lung tissue from patients with mild-moderate COPD at single-cell resolution. Methods: We performed single-cell transcriptomic, proteomic, and T-cell receptor repertoire analyses on lung tissue from patients with mild-moderate COPD (n = 5, Global Initiative for Chronic Obstructive Lung Disease I or II), emphysema without airflow obstruction (n = 5), end-stage COPD (n = 2), control (n = 6), or donors (n = 4). We validated in an independent patient cohort (N = 929) and integrated with the Hhip+/- murine model of COPD. Measurements and Main Results: Mild-moderate COPD lungs have increased abundance of two CD8+ T cell subpopulations: cytotoxic KLRG1+TIGIT+CX3CR1+ TEMRA (T effector memory CD45RA+) cells, and DNAM-1+CCR5+ T resident memory (TRM) cells. These CD8+ T cells interact with myeloid and alveolar type II cells via IFNG and have hyperexpanded T-cell receptor clonotypes. In an independent cohort, the CD8+KLRG1+ TEMRA cells are increased in mild-moderate COPD lung compared with control or end-stage COPD lung. Human CD8+KLRG1+ TEMRA cells are similar to CD8+ T cells driving inflammation in an aging-related murine model of COPD. Conclusions: CD8+ TEMRA cells are increased in mild-moderate COPD lung and may contribute to inflammation that precedes severe disease. Further study of these CD8+ T cells may have therapeutic implications for preventing severe COPD.

Muscle fiber necroptosis in pathophysiology of idiopathic inflammatory myopathies and its potential as target of novel treatment strategy.

Idiopathic inflammatory myopathies (IIMs), which are a group of chronic and diverse inflammatory diseases, are primarily characterized by weakness in the proximal muscles that progressively leads to persistent disability. Current treatments of IIMs depend on nonspecific immunosuppressive agents (including glucocorticoids and immunosuppressants). However, these therapies sometimes fail to regulate muscle inflammation, and some patients suffer from infectious diseases and other adverse effects related to the treatment. Furthermore, even after inflammation has subsided, muscle weakness persists in a significant proportion of the patients. Therefore, the elucidation of pathophysiology of IIMs and development of a better therapeutic strategy that not only alleviates muscle inflammation but also improves muscle weakness without increment of opportunistic infection is awaited. Muscle fiber death, which has been formerly postulated as "necrosis", is a key histological feature of all subtypes of IIMs, however, its detailed mechanisms and contribution to the pathophysiology remained to be elucidated. Recent studies have revealed that muscle fibers of IIMs undergo necroptosis, a newly recognized form of regulated cell death, and promote muscle inflammation and dysfunction through releasing inflammatory mediators such as damage-associated molecular patterns (DAMPs). The research on murine model of polymyositis, a subtype of IIM, revealed that the inhibition of necroptosis or HMGB1, one of major DAMPs released from muscle fibers undergoing necroptosis, ameliorated muscle inflammation and recovered muscle weakness. Furthermore, not only the necroptosis-associated molecules but also PGAM5, a mitochondrial protein, and reactive oxygen species have been shown to be involved in muscle fiber necroptosis, indicating the multiple target candidates for the treatment of IIMs acting through necroptosis regulation. This article overviews the research on muscle injury mechanisms in IIMs focusing on the contribution of necroptosis in their pathophysiology and discusses the potential treatment strategy targeting muscle fiber necroptosis.

Apple-shaped obesity: A risky soil for cytokine-accelerated severity in COVID-19.

Obesity has been recognized as one of the most significant risk factors for the deterioration and mortality associated with COVID-19, but the significance of obesity itself differs among ethnicity. Multifactored analysis of our single institute-based retrospective cohort revealed that high visceral adipose tissue (VAT) burden, but not other obesity-associated markers, was related to accelerated inflammatory responses and the mortality of Japanese COVID-19 patients. To elucidate the mechanisms how VAT-dominant obesity induces severe inflammation after severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection, we infected two different strains of obese mice, C57BL/6JHamSlc-ob/ob (ob/ob), C57BLKS/J-db/db (db/db), genetically impaired in the leptin ligand and receptor, respectively, and control C57BL/6 mice with mouse-adapted SARS-CoV-2. Here, we revealed that VAT-dominant ob/ob mice were extremely more vulnerable to SARS-CoV-2 due to excessive inflammatory responses when compared to SAT-dominant db/db mice. In fact, SARS-CoV-2 genome and proteins were more abundant in the lungs of ob/ob mice, engulfed in macrophages, resulting in increased cytokine production including interleukin (IL)-6. Both an anti-IL-6 receptor antibody treatment and the prevention of obesity by leptin replenishment improved the survival of SARS-CoV-2-infected ob/ob mice by reducing the viral protein burden and excessive immune responses. Our results have proposed unique insights and clues on how obesity increases the risk of cytokine storm and death in patients with COVID-19. Moreover, earlier administration of antiinflammatory therapeutics including anti-IL-6R antibody to VAT-dominant patients might improve clinical outcome and stratification of the treatment for COVID-19, at least in Japanese patients.

Factors associated with impaired physical function in elderly rheumatoid arthritis patients who had achieved low disease activity.

OBJECTIVE: We aimed to investigate factors associated with impaired physical function (defined as HAQ Disability Index [HAQ-DI] >0.5) of old-old (aged 75-84) patients with rheumatoid arthritis (RA). METHODS: Data from 15,185 RA patients in the National Database of Rheumatic Disease in Japan were extracted from 2017 to 2018. We enrolled 3,708 patients aged 55-84 in simplified disease activity index (SDAI) ≤11 and Steinbrocker stage I/II. Factors associated with HAQ-DI >0.5 were analyzed by multivariable logistic regression. RESULTS: About half of the old-old patients received methotrexate, which was lower than middle-aged (55-64) and young-old patients (65-74). The proportion of glucocorticoids in the old-old patients was highest among the three groups, and biological disease-modifying anti-rheumatic drugs were similarly used. The prevalence of HAQ-DI >0.5 was significantly higher in old-old patients with low disease activity than in those with remission. The same was true in the middle-aged and young-old patients. Multivariable analysis showed age, higher SDAI, glucocorticoid use, and methotrexate non-use were significantly associated with HAQ-DI >0.5 in the old-old patients. CONCLUSIONS: SDAI remission was an ideal goal for old-old patients in terms of physical function. Glucocorticoids and a low proportion of methotrexate use may influence the physical function of old-old patients.

Amelioration of inflammatory myopathies by glucagon-like peptide-1 receptor agonist via suppressing muscle fibre necroptosis.

BACKGROUND: As glucocorticoids induce muscle atrophy during the treatment course of polymyositis (PM), novel therapeutic strategy is awaited that suppresses muscle inflammation but retains muscle strength. We recently found that injured muscle fibres in PM undergo FASLG-mediated necroptosis, a form of regulated cell death accompanied by release of pro-inflammatory mediators, contributes to accelerate muscle inflammation and muscle weakness. Glucagon-like peptide-1 receptor (GLP-1R) agonists have pleiotropic actions including anti-inflammatory effects, prevention of muscle atrophy, and inhibition of cell death, in addition to anti-diabetic effect. We aimed in this study to examine the role of GLP-1R in PM and the effect of a GLP-1R agonist on in vivo and in vitro models of PM. METHODS: Muscle specimens of PM patients and a murine model of PM, C protein-induced myositis (CIM), were examined for the expression of GLP-1R. The effect of PF1801, a GLP-1R agonist, on CIM was evaluated in monotherapy or in combination with prednisolone (PSL). As an in vitro model of PM, C2C12-derived myotubes were treated with FASLG to induce necroptosis. The effect of PF1801 on this model was analysed. RESULTS: GLP-1R was expressed on the inflamed muscle fibres of PM and CIM. The treatment of CIM with PF1801 in monotherapy (PF) or in combination with PSL (PF + PSL) suppressed CIM-induced muscle weakness (grip strength, mean ± SD (g); PF 227 ± 6.0 (P < 0.01), PF + PSL 224 ± 8.5 (P < 0.01), Vehicle 162 ± 6.0) and decrease in cross-sectional area of muscle fibres (mean ± SD (µm2 ); PF 1896 ± 144 (P < 0.05), PF + PSL 2018 ± 445 (P < 0.01), Vehicle 1349 ± 199) as well as the severity of histological inflammation scores (median, interquartile range; PF 0.0, 0.0-0.5 (P < 0.05), PF + PSL 0.0, 0.0-0.0 (P < 0.01), Vehicle 1.9, 1.3-3.3). PF1801 decreased the levels of inflammatory mediators such as TNFα, IL-6, and HMGB1 in the serum of CIM. PF1801 inhibited necroptosis of the myotubes in an AMP-activated protein kinase (AMPK)-dependent manner. PF1801 activated AMPK and decreased the expression of PGAM5, a mitochondrial protein, which was crucial for necroptosis of the myotubes. PF1801 promoted the degradation of PGAM5 through ubiquitin-proteasome activity. Furthermore, PF1801 suppressed FASLG-induced reactive oxygen species (ROS) accumulation in myotubes, also crucial for the execution of necroptosis, thorough up-regulating the antioxidant molecules including Nfe2l2, Hmox1, Gclm, and Nqo1. CONCLUSIONS: GLP-1R agonist could be a novel therapy for PM that recovers muscle weakness and suppresses muscle inflammation through inhi biting muscle fibre necroptosis.

Refractory antiphospholipid antibody syndrome-induced thrombocytopaenia successfully treated with belimumab.

Antiphospholipid antibody syndrome (APS) is an autoimmune disease with clinical symptoms such as recurrent arterial/venous thrombosis, pregnancy morbidities and thrombocytopaenia. Antiphospholipid antibodies are suggested to be involved in the pathological condition of APS. Therefore, belimumab (BLM), which reduces autoantibody production from B cells, is expected to be effective in the treatment of APS.We report a case of a 63-years-old woman with APS with refractory thrombocytopaenia. Her thrombocytopaenia did not respond to antithrombotic therapy and immunosuppressive treatment including corticosteroids and rituximab but improved with BLM. This is the first report of an APS-induced thrombocytopaenia treated successfully with BLM. BLM should be an effective treatment for APS-related thrombocytopaenia.

Targeting necroptosis in muscle fibers ameliorates inflammatory myopathies.

Muscle cell death in polymyositis is induced by CD8+ cytotoxic T lymphocytes. We hypothesized that the injured muscle fibers release pro-inflammatory molecules, which would further accelerate CD8+ cytotoxic T lymphocytes-induced muscle injury, and inhibition of the cell death of muscle fibers could be a novel therapeutic strategy to suppress both muscle injury and inflammation in polymyositis. Here, we show that the pattern of cell death of muscle fibers in polymyositis is FAS ligand-dependent necroptosis, while that of satellite cells and myoblasts is perforin 1/granzyme B-dependent apoptosis, using human muscle biopsy specimens of polymyositis patients and models of polymyositis in vitro and in vivo. Inhibition of necroptosis suppresses not only CD8+ cytotoxic T lymphocytes-induced cell death of myotubes but also the release of inflammatory molecules including HMGB1. Treatment with a necroptosis inhibitor or anti-HMGB1 antibodies ameliorates myositis-induced muscle weakness as well as muscle cell death and inflammation in the muscles. Thus, targeting necroptosis in muscle cells is a promising strategy for treating polymyositis providing an alternative to current therapies directed at leukocytes.

Arterial and Venous Thrombosis Complicated in COVID-19: A Retrospective Single Center Analysis in Japan.

Background: Thrombosis is a characteristic complication in coronavirus disease 2019 (COVID-19). Since coagulopathy has been observed over the entire clinical course, thrombosis might be a clue to understanding the specific pathology in COVID-19. Currently, there is limited epidemiological data of COVID-19-associated thrombosis in the Japanese population and none regarding variant strains of SARS-CoV-2. Here, we elucidate the risk factors and the pattern of thrombosis in COVID-19 patients. Methods: The patients consecutively admitted to Tokyo Medical and Dental University Hospital with COVID-19 were retrospectively analyzed. SARS-CoV-2 variants of concern/interest (VOC/VOI) carrying the spike protein mutants E484K, N501Y, or L452R were identified by PCR-based analysis. All thrombotic events were diagnosed by clinical symptoms, ultrasonography, and/or radiological tests. Results: Among the 516 patients, 32 patients experienced 42 thromboembolic events. Advanced age, severe respiratory conditions, and several abnormal laboratory markers were associated with the development of thrombosis. While thrombotic events occurred in 13% of the patients with a severe respiratory condition, those events still occurred in 2.5% of the patients who did not require oxygen therapy. Elevated D-dimer and ferritin levels on admission were independent risk factors of thrombosis (adjusted odds ratio 9.39 and 3.11, 95% confidence interval 2.08-42.3, and 1.06-9.17, respectively). Of the thrombotic events, 22 were venous, whereas 20 were arterial. While patients with thrombosis received anticoagulation and antiinflammatory therapies with a higher proportion, the mortality rate, organ dysfunctions, and bleeding complications in these patients were higher than those without thrombosis. The incidence of thrombosis in COVID-19 became less frequent over time, such as during the replacement of the earlier strains of SARS-CoV-2 by VOC/VOI and during increased use of anticoagulatory therapeutics. Conclusion: This study elucidated that elevated D-dimer and ferritin levels are useful biomarkers of thrombosis in COVID-19 patients. The comparable incidence of arterial thrombosis with venous thrombosis and the development of thrombosis in less severe patients required further considerations for the management of Japanese patients with COVID-19. Further studies would be required to identify high-risk populations and establish appropriate interventions for thrombotic complications in COVID-19.

Effectiveness and safety of treat-to-target strategy in elderly-onset rheumatoid arthritis: a 3-year prospective observational study.

OBJECTIVES: To evaluate 3-year outcomes of following a treat-to-target (T2T) strategy targeting low disease activity for patients with elderly-onset RA (EORA) and to confirm safety profile of T2T. METHODS: Treatment was adjusted to target low disease activity with conventional synthetic DMARDs, followed by biologic DMARDs (bDMARDs) in 197 MTX-naïve EORA patients (mean age 74.9 years) with moderate-to-high disease activity. Non-implementation of T2T was evaluated at week 12, 24, 36, 52, 76, 104 and 128. To evaluate risks of using MTX, bDMARDs and glucocorticoids, 2122 periods of 3 months each were analysed using Bayesian hierarchical logistic regression models. RESULTS: Of the patients, 84.7% received methotrexate, 34.0% glucocorticoids with DMARDs and 41.6% bDMARDs during the observation period. Sixty-nine of the 197 patients failed to adhere to T2T because of comorbidities or the patient's own decision: 33 failed once, 19 twice, 10 three times and 6 four times or more. Simplified disease activity index (SDAI) remission and HAQ Disability Index (HAQ-DI) ≤0.5 at 3 years were achieved in 57.8% and 70.3% of the 128 patients adhering to T2T, and 34.8% and 43.5% of the 69 patients who did not adhere to T2T, respectively, and these were significantly different. Eighty-nine serious adverse events (SAEs) of any type were reported in 61 patients. MTX, bDMARDs and glucocorticoid were not associated with SAEs when adjusted for mean SDAI during the observation period and comorbidities at baseline. CONCLUSION: T2T strategy for EORA by using MTX and bDMARDs was effective with an acceptable safety profile. Adhering to T2T led to better outcomes.

A new in vitro model of polymyositis reveals CD8+ T cell invasion into muscle cells and its cytotoxic role.

OBJECTIVES: The hallmark histopathology of PM is the presence of CD8+ T cells in the non-necrotic muscle cells. The aim of this study was to clarify the pathological significance of CD8+ T cells in muscle cells. METHODS: C2C12 cells were transduced retrovirally with the genes encoding MHC class I (H2Kb) and SIINFEKL peptide derived from ovalbumin (OVA), and then differentiated to myotubes (H2KbOVA-myotubes). H2KbOVA-myotubes were co-cultured with OT-I CD8+ T cells derived from OVA-specific class I restricted T cell receptor transgenic mice as an in vitro model of PM to examine whether the CD8+ T cells invade into the myotubes and if the myotubes with the invasion are more prone to die than those without. Muscle biopsy samples from patients with PM were examined for the presence of CD8+ T cells in muscle cells. The clinical profiles were compared between the patients with and without CD8+ T cells in muscle cells. RESULTS: Analysis of the in vitro model of PM with confocal microscopy demonstrated the invasion of OT-I CD8+ T cells into H2KbOVA-myotubes. Transmission electron microscopic analysis revealed an electron-lucent area between the invaded CD8+ T cell and the cytoplasm of H2KbOVA-myotubes. The myotubes invaded with OT-I CD8+ T cells died earlier than the uninvaded myotubes. The level of serum creatinine kinase was higher in patients with CD8+ T cells in muscle cells than those without these cells. CONCLUSION: CD8+ T cells invade into muscle cells and contribute to muscle injury in PM. Our in vitro model of PM is useful to examine the mechanisms underlying muscle injury induced by CD8+ T cells.

Allergic bronchopulmonary aspergillosis in a patient with rheumatoid arthritis under adalimumab therapy: a case report.

A 77-year-old woman with a 15-year history of rheumatoid arthritis (RA) was admitted to our hospital because of a wet cough that persisted for 1 month. The patient had been taking methotrexate (MTX) and adalimumab (ADA) for the past 3 years, and disease activity of RA was low. Discontinuation of ADA and MTX and treatment with oral levofloxacin were not effective. On admission, laboratory examinations showed eosinophilia (2539/µL), elevated serum total immunoglobulin E (538.0 IU/ml) and Aspergillus-specific immunoglobulin E levels, and Aspergillus fumigatus serum precipitins. A chest radiograph revealed multiple bilateral pulmonary shadows, and computed tomography revealed multiple consolidations. Bronchoscopic examination showed mucous plugs. Pathological examination revealed diffuse infiltration of eosinophils and fungus in the plugs. These findings led to the diagnosis of allergic bronchopulmonary aspergillosis (ABPA). A combination of prednisolone (0.5 mg/kg/day) and itraconazole (200 mg/day) was administered. After 3 months, the pulmonary consolidations resolved. To our knowledge, this is the first report of ABPA in a patient with RA treated with ADA. If patients treated with biologic disease-modifying antirheumatic drugs present with eosinophilia and pulmonary consolidations, clinicians should consider ABPA in the differential diagnosis.

IgG4-Related Sialoadenitis with a Skin Lesion and Multiple Mononeuropathies Suggesting Coexistent Cryoglobulinemic Vasculitis.

A 68-year-old man was admitted because of weakness of the left leg, dysesthesiae of the extremities and bilateral lower extremity purpura. A neurological examination showed mononeuritis multiplex with laboratory evidence of hypocomplementemia, cryoglobulinemia and leukocytoclastic vasculitis in the biopsy of a skin specimen. The patient also exhibited bilateral submandibular gland swelling, elevated serum IgG4 levels and infiltration of a large number of IgG4-positive plasma cells in the submandibular glands. These findings were consistent with both cryoglobulinemic vasculitis and IgG4-related disease. The administration of oral prednisolone (1 mg/kg/day) resolved the neurological manifestations and the swelling of the submandibular glands and cryoglobulinemia.

Acute Tubulointerstitial Nephritis Associated with Infliximab in a Patient with Crohn's Disease.

We report the findings of a 46-year-old man, who presented with fever and renal dysfunction while undergoing treatment for Crohn's disease with infliximab (IFX). Remittent fever and renal dysfunction with urinary casts developed and lasted for 3 weeks without deterioration of Crohn's disease. Renal biopsy revealed acute tubulointerstitial nephritis (ATIN). After the discontinuation of IFX, his fever and renal abnormalities resolved. We herein report the first known case of ATIN associated with IFX.

[Atherosclerotic and hemorrhagic diseases in a patient with primary immune deficiency].

A 59-year-old man, who suffered from periodic fever with continuous elevation of the C-reactive protein (CRP) level was referred to our hospital. He had frequent respiratory infections and diarrhea since his childhood. The serum immunoglobulin (Ig) G level was low (537 mg/dl) while IgA and IgE were undetectable. The serum IgM level was elevated (737 mg/dl). Based on these clinical features, he was diagnosed with primary immune deficiency, hyper IgM syndrome. He had past histories of aortic aneurysm, which had been repaired surgically in his fifties. His persistent proteinuria made us to perform renal biopsy, which revealed nephrosclerotic changes. During the hospitalization, multiple events of subcortical brain hemorrhage, subarachnoid hemorrhage, and pulmonary alveolar hemorrhage occurred. Bleeding time and coagulation tests were normal. Antinuclear antibody, anti-neutrophil cytoplasmic antibody, or anti-cardiolipin antibody was absent. Herein, we described the first case of the immune deficiency associated with severe arteriosclerosis and hemorrhage.