Published papers

© 2019, The Author(s), under exclusive licence to Springer Nature Limited. Interleukin (IL)-2 is a pleiotropic cytokine that is necessary to prevent chronic inflammation in the gastrointestinal tract 1–4 . The protective effects of IL-2 involve the generation, maintenance and function of regulatory T (T reg ) cells 4–8 , and the use of low doses of IL-2 has emerged as a potential therapeutic strategy for patients with inflammatory bowel disease 9 . However, the cellular and molecular pathways that control the production of IL-2 in the context of intestinal health are undefined. Here we show, in a mouse model, that IL-2 is acutely required to maintain T reg cells and immunological homeostasis throughout the gastrointestinal tract. Notably, lineage-specific deletion of IL-2 in T cells did not reduce T reg cells in the small intestine. Unbiased analyses revealed that, in the small intestine, group-3 innate lymphoid cells (ILC3s) are the dominant cellular source of IL-2, which is induced selectively by IL-1β. Macrophages in the small intestine produce IL-1β, and activation of this pathway involves MYD88- and NOD2-dependent sensing of the microbiota. Our loss-of-function studies show that ILC3-derived IL-2 is essential for maintaining T reg cells, immunological homeostasis and oral tolerance to dietary antigens in the small intestine. Furthermore, production of IL-2 by ILC3s was significantly reduced in the small intestine of patients with Crohn’s disease, and this correlated with lower frequencies of T reg cells. Our results reveal a previously unappreciated pathway in which a microbiota- and IL-1β-dependent axis promotes the production of IL-2 by ILC3s to orchestrate immune regulation in the intestine.

The neural and immune systems are closely connected, and recently, their molecular mechanisms and relationships with diseases have attracted substantial attention. Particularly, it has been increasingly reported that ILC2s, which produce type 2 cytokines independent of acquired immunity, are regulated by neuropeptides such as catecholamines, acetylcholine, vasoactive intestinal peptide, neuromedins, and calcitonin gene-related peptide. However, the regulatory mechanisms in this regard are only partially understood, implying that further studies are still needed to clarify the complete mechanisms and processes. In this review, we summarize current reports on the regulatory effect of neuropeptides on ILC2s, some of which have conflicting results, possibly owing to the complexity of G-protein coupled receptors. By summarizing the current evidence, we hope to be able to identify what is currently unknown as well as what needs to be clarified in the future.

The genetic make-up of an individual contributes to the susceptibility and response to viral infection. Although environmental, clinical and social factors have a role in the chance of exposure to SARS-CoV-2 and the severity of COVID-191,2, host genetics may also be important. Identifying host-specific genetic factors may reveal biological mechanisms of therapeutic relevance and clarify causal relationships of modifiable environmental risk factors for SARS-CoV-2 infection and outcomes. We formed a global network of researchers to investigate the role of human genetics in SARS-CoV-2 infection and COVID-19 severity. Here we describe the results of three genome-wide association meta-analyses that consist of up to 49,562 patients with COVID-19 from 46 studies across 19 countries. We report 13 genome-wide significant loci that are associated with SARS-CoV-2 infection or severe manifestations of COVID-19. Several of these loci correspond to previously documented associations to lung or autoimmune and inflammatory diseases3–7. They also represent potentially actionable mechanisms in response to infection. Mendelian randomization analyses support a causal role for smoking and body-mass index for severe COVID-19 although not for type II diabetes. The identification of novel host genetic factors associated with COVID-19 was made possible by the community of human genetics researchers coming together to prioritize the sharing of data, results, resources and analytical frameworks. This working model of international collaboration underscores what is possible for future genetic discoveries in emerging pandemics, or indeed for any complex human disease.

Coronavirus disease 2019 (COVID-19) often causes radiological and functional pulmonary sequelae. However, evidence on 1-year follow-up of pulmonary sequelae is limited. We aimed to investigate the characteristics and time-course of pulmonary sequelae after recovery from COVID-19 through 1-year follow-up. We searched PubMed and EMBASE databases on 25 February 2022, and included studies with computed tomography (CT) findings at the 1-year follow-up. The extracted data on CT findings were analysed using a one-group meta-analysis. We further analysed the data in relation to COVID-19 severity, improvement rate and lung function. Fifteen eligible studies (N = 3134) were included. One year after COVID-19, 32.6% (95% CI 24.0–42.6, I2 = 92.9%) presented with residual CT abnormalities. Ground-glass opacity and fibrotic-like changes were frequently observed in 21.2% (95% CI 15.4–28.4, I2 = 86.7%) and 20.6% (95% CI 11.0–35.2, I2 = 91.9%), respectively. While the gradual recovery was seen on CT (52.9% [mid-term] vs. 32.6% [1 year]), the frequency of CT abnormalities was higher in the severe/critical cases than in the mild/moderate cases (37.7% vs. 20.7%). In particular, fibrotic changes showed little improvement between 4–7 months and 1 year after COVID-19. Pulmonary function tests at 1 year also showed the decline in diffusing capacity of the lung for carbon monoxide, especially in severe/critical cases. Our meta-analysis indicated that residual CT abnormalities were common in hospitalized COVID-19 patients 1 year after recovery, especially fibrotic changes in severe/critical cases. As these sequelae may last long, vigilant observations and longer follow-up periods are warranted.

Group 2 innate lymphoid cells (ILC2s) are GATA3-expressing type 2 cytokine-producing innate lymphocytes that are present in various organs throughout the body. Basically, ILC2s are tissue-resident cells associated with a variety of pathological conditions in each tissue. Differences in the tissue-specific properties of ILC2s are formed by the post-natal tissue environment; however, diversity exists among ILC2s within each localized tissue due to developmental timing and activation. Diversity between steady-state and activated ILC2s in mice and humans has been gradually clarified with the advancement of single-cell RNA-seq technology. Another layer of complexity is that ILC2s can acquire other ILC-like functions, depending on their tissue environment. Further, ILC2s with immunological memory and exhausted ILC2s are both present in tissues, and the nature of ILC2s varies with senescence. To clarify how ILC2s affect human diseases, research should be conducted with a comprehensive understanding of ILC2s, taking into consideration the diversity of ILC2s rather than a snapshot of a single section. In this review, we summarize the current understanding of the heterogeneity of ILC2s in the lungs and highlight a novel field of immunology.

Case Presentation: A 70-year-old woman who had received a diagnosis of pneumonia in the right lower lobe was treated with antibiotics at a general practitioner's clinic 9 months earlier. Her pneumonia had improved, but the cough and lung infiltrates persisted for > 6 months, so the patient was referred to our hospital. She had undergone surgery for breast cancer 30 years earlier but had no other medical history. She was not taking any medications and had no history of smoking, including passive smoking.

Inhalers are commonly used to treat asthma and chronic obstructive pulmonary disease. Regular and correct usage of inhalers is necessary for effective use. However, approximately 70% of patients do not use their inhalers as directed. This is due to a lack of understanding about the medication and misunderstanding of directions. Assessment of patients’ inhaler techniques are usually conducted in person. However, doctors or pharmacists have no objective information regarding how patients use their inhalers at home. Therefore, monitoring daily inhaler use is necessary for precise medical treatment. This article proposes an inhalation monitoring device using an inertial measurement unit (IMU). The IMU is used to measure a patient’s inhalation motion. Incorrect inhalation usage can be determined by comparing the measurement data against data that indicate correct usage. The experimental results show the utility of the proposed device.

Objective: To assess the effects of statins on asthma by systematically reviewing and conducting a meta-analysis on all clinical studies, including randomized controlled trials (RCTs) and observational studies, that examined the effects of statins on asthma. Methods: PubMed, EMBASE databases, and Cochrane reviews were searched to identify RCTs and observational studies, conducted through June 16, 2020, that assessed the effect of statins as a treatment for asthma. A meta-analysis was conducted using the following main outcomes: asthma control test (ACT), asthma control questionnaire (ACQ), pre- and post-bronchodilator forced expiratory volume in one second (FEV1), peak flow (PEF), and asthma exacerbation (asthma-related emergency department (ED) visits and hospitalization). Results: Our search revealed 11 RCTs and 8 observational studies that met the inclusion criteria. A meta-analysis demonstrated that statin treatment significantly improved ACT scores (mean difference: 1.61, P < 0.001) and ACQ scores (mean difference: −0.38, P < 0.001) compared to a placebo. Furthermore, statin treatment significantly reduced asthma-related ED visits (hazard ratio [HR], 95% confidence interval [CI], 0.83 [0.75–0.92], P < 0.001, number needed to treat [NNT], 5.9). However, statin treatment did not improve pulmonary function (FEV1 and PEF). Conclusion: Our results suggest that statins have the potential to improve asthma control and reduce asthma exacerbation without any improvement in pulmonary function. Supplemental data for this article can be accessed at publisher’s website.

Chronic obstructive pulmonary disease (COPD) is primarily caused by inhalation of cigarette smoke and is the third leading cause of death worldwide. Pulmonary surfactant, a complex of phospholipids and proteins, plays an essential role in respiration by reducing the surface tension in the alveoli. Lysophosphatidylcholine acyltransferase 1 (LPCAT1) is an enzyme that catalyzes the biosynthesis of surfactant lipids and is expressed in type 2 alveolar epithelial cells. Its dysfunction is suggested to be involved in various lung diseases; however, the relationship between LPCAT1 and COPD remains unclear. To investigate the role of LPCAT1 in the pathology of COPD, we analyzed an elastase-induced emphysema model using Lpcat1 knockout (KO) mice. In Lpcat1 KO mice, elastase-induced emphysema was significantly exacerbated with increased apoptotic cells, which was not ameliorated by supplementation with dipalmitoylphosphatidylcholine, which is a major component of the surfactant synthesized by LPCAT1. We subsequently evaluated the effects of cigarette smoking on primary human type 2 alveolar epithelial cells (hAEC2s) and found that cigarette smoke extract (CSE) downregulated the expression of Lpcat1. Furthermore, RNA sequencing analysis revealed that the apoptosis pathway was significantly enriched in CSE-treated primary hAEC2s. Finally, we downregulated the expression of Lpcat1 using small interfering RNA, which resulted in enhanced CSE-induced apoptosis in A549 cells. Taken together, cigarette smoke–induced downregulation of LPCAT1 can promote the exacerbation of pulmonary emphysema by increasing the susceptibility of alveolar epithelial cells to apoptosis, thereby suggesting that Lpcat1 is a novel therapeutic target for irreversible emphysema.

Copyright © 2020 Ueki et al. Guidelines from the CDC and the WHO recommend the wearing of face masks to prevent the spread of coronavirus (CoV) disease 2019 (COVID-19); however, the protective efficiency of such masks against airborne transmission of infectious severe acute respiratory syndrome CoV-2 (SARS-CoV-2) droplets/aerosols is unknown. Here, we developed an airborne transmission simulator of infectious SARS-CoV-2-containing droplets/aerosols produced by human respiration and coughs and assessed the transmissibility of the infectious droplets/aerosols and the ability of various types of face masks to block the transmission. We found that cotton masks, surgical masks, and N95 masks all have a protective effect with respect to the transmission of infective droplets/aerosols of SARS-CoV-2 and that the protective efficiency was higher when masks were worn by a virus spreader. Importantly, medical masks (surgical masks and even N95 masks) were not able to completely block the transmission of virus droplets/aerosols even when completely sealed. Our data will help medical workers understand the proper use and performance of masks and determine whether they need additional equipment to protect themselves from infected patients.IMPORTANCE Airborne simulation experiments showed that cotton masks, surgical masks, and N95 masks provide some protection from the transmission of infective SARS-CoV-2 droplets/aerosols; however, medical masks (surgical masks and even N95 masks) could not completely block the transmission of virus droplets/aerosols even when sealed.

Background: Some academic organizations recommended that physicians intubate patients with COVID-19 with a relatively lower threshold of oxygen usage particularly in the early phase of pandemic. We aimed to elucidate whether early intubation is associated with decreased in-hospital mortality among patients with novel coronavirus disease 2019 (COVID-19) who required intubation. Methods: A multicenter, retrospective, observational study was conducted at 66 hospitals in Japan where patients with moderate-to-severe COVID-19 were treated between January and September 2020. Patients who were diagnosed as COVID-19 with a positive reverse-transcription polymerase chain reaction test and intubated during admission were included. Early intubation was defined as intubation conducted in the setting of ≤ 6 L/min of oxygen usage. In-hospital mortality was compared between patients with early and non-early intubation. Inverse probability weighting analyses with propensity scores were performed to adjust patient demographics, comorbidities, hemodynamic status on admission and time at intubation, medications before intubation, severity of COVID-19, and institution characteristics. Subgroup analyses were conducted on the basis of age, severity of hypoxemia at intubation, and days from admission to intubation. Results: Among 412 patients eligible for the study, 110 underwent early intubation. In-hospital mortality was lower in patients with early intubation than those with non-early intubation (18 [16.4%] vs. 88 [29.1%]; odds ratio, 0.48 [95% confidence interval 0.27–0.84]; p = 0.009, and adjusted odds ratio, 0.28 [95% confidence interval 0.19–0.42]; p < 0.001). The beneficial effects of early intubation were observed regardless of age and severity of hypoxemia at time of intubation; however, early intubation was associated with lower in-hospital mortality only among patients who were intubated later than 2 days after admission. Conclusions: Early intubation in the setting of ≤ 6 L/min of oxygen usage was associated with decreased in-hospital mortality among patients with COVID-19 who required intubation. Trial Registration None.

The recent discovery of new innate lymphoid cells (ILCs) has revolutionized the field of allergies. Since most allergic diseases induce a type 2 immune response, Th2 cells, which produce IL-4, IL-5, and IL-13 in an antigen-dependent manner, in addition to basophils and mast cells which are activated by antigen-specific IgE, are thought to play a major role in the pathogenesis. However, since group 2 innate lymphoid cells (ILC2s) produce type 2 cytokines (i.e., IL-2, IL-4, IL-5, IL-6, IL-9, IL-13, GM-CSF, and amphiregulin) in response to various cytokines, including IL-33 in the surrounding environment, the possibility has emerged that there are two types of allergies: allergies induced in an antigen-dependent manner by Th2 cells and allergies induced in an antigen-independent manner by ILC2s. In order to make an impact on the increasing incidence of allergic diseases in the world, it is essential to research and develop new treatments that focus not only on Th2 cells but also on ILC2s. In this chapter, the role of ILCs in allergic diseases, which has rapidly changed with the discovery of ILCs, is discussed, focusing mainly on ILC2s.

A 56-year-old woman presented with repeated swelling of the lips and face. She had a history of childhood asthma; she had a recurrence of asthma when she was 54 years old and was taking inhaled corticosteroids, and other antiasthma drugs. The swelling of her lips and face improved temporarily with oral corticosteroids (OCS), but recurred soon after discontinuing OCS. Her peripheral blood eosinophil count was 632/μL (9.3%), and her serum was negative for myeloperoxidase-anti-neutrophil cytoplasmic antibody and serine proteinase3-anti-neutrophil cytoplasmic antibody. Hematoxylin and eosin staining of her back skin revealed abundant eosinophilic infiltrate around the vascular area of the shallow dermis layer, but no evidence of vasculitis and we diagnosed her as eosinophilic annular erythema (EAE). Punctate staining of galectin-10, chromatolytic eosinophils, and net-like DNA was also evident in close proximity to the free granules, indicating extracellular vesicles and eosinophil extracellular traps (ETosis). We started daily OCS to control her asthma and skin eruption/oedema. Three months after administering daily OCS, benralizumab was initiated for withdrawal from OCS dependence and treatment of severe asthma. After initiation of benralizumab, her skin and subcutaneous tissue symptoms promptly improved. OCS was discontinued, and no edematous erythema has been observed since then. Bronchial asthma has also been well-controlled. This is the first report on the evidence of eosinophil ETosis in the dermis of EAE patients and the efficacy of benralizumab in a patient with EAE. Benralizumab may be a useful drug for treating refractory EAE with severe eosinophilic asthma.

Food allergy is a typical immediate-onset allergic disease in which symptoms are provoked by exposure to the sensitized antigens. Although previous reports have shown that omalizumab has helped children with egg or milk allergy achieve oral immunotherapy safely, there is still no established method for induction of remission in adult food allergy. A 51-year-old woman with oral steroid-dependent severe asthma was treated with omalizumab for 6 years. She had shellfish and wheat food allergy and oral allergy syndrome induced by kiwi and other foods associated with latex-fruit syndrome. Since omalizumab treatment, her food allergy symptoms had disappeared. After 7 years of this treatment, disseminated erythema suddenly appeared; omalizumab was discontinued because of suspected drug-induced eruption. After omalizumab interruption, she felt an itching sensation in her throat with worsened asthma control immediately after wheat ingestion. Readministration of omalizumab improved these symptoms. Thus, we raised the possibility that omalizumab not only improved asthma control but also induced pharmacological remission of the patient's food allergy. Omalizumab may be considered as a treatment option for adult patients with food allergies and severe asthma.

Background and design:: The coronavirus disease (COVID-19) pandemic is having a devastating effect worldwide. Host genome differences between populations may influence the severity of COVID-19. The Japan COVID-19 Task Force is conducting host genome analysis of hospitalized patients with COVID-19 from more than 70 institutions nationwide in Japan. This report describes the clinical characteristics of patients enrolled to date. Results:: The median (interquartile range) age of the 1674 patients included in the analysis was 59 (45–71) years, and more than half of the patients (66.2%) were male. Less than half of the patients (41.2%) had severe disease. The case fatality rate was 3.2%. Conclusions:: Since this is a hospital-based study, the number of severe cases was relatively high, but the case fatality rate was relatively low, when compared to that of other countries. In the future, we will continue to enroll patients and conduct genome analyses of patients with COVID-19.

Introduction The rapid spread of COVID-19 posed a global burden. Substantial number of people died of the disease in the acute phase of infection. In addition, a significant proportion of patients have been reported to suffer from post-acute phase symptoms, sequelae of COVID-19, which may negatively influence the quality of daily living and/or socioeconomic circumstances of the patients. However, no previous study has comprehensively and objectively assessed the quality of life of patients by using existing international scales. Further, evidence of socioeconomic consequences among patients with COVID-19 is scarce. To address the multidimensional issues from sequelae of COVID-19, evidence from comprehensive surveys beyond clinical perspectives is critical that investigates health, and social determinants of disease progression as well as socioeconomic consequences at a large scale. Methods and analysis In this study, we plan to conduct a nationwide and comprehensive survey for the sequelae of COVID-19 in a total of 1000 patients diagnosed at 27 hospitals throughout Japan. This study will evaluate not only the health-related status of patients from clinical perspectives but also the Health-related Quality of Life (HRQoL) scores, socioeconomic status and consequences to discuss the sequelae of the disease and the related risk factors. The primary endpoint is the frequency of long-term complications of COVID-19 infection. The secondary endpoints are risk factors for progression to sequelae of COVID-19 infection. The study will provide robust and important evidence as a resource to tackle the issues from the sequelae of COVID-19 from the multi-dimensional perspectives. Ethics and dissemination This trial was approved by the Keio University School of Medicine Ethics Committee (20200243, UMIN000042299). The results of this study will be reported at a society meeting or published in a peer-reviewed journal.

Group 2 innate lymphoid cells (ILC2s) play an important role in the pathophysiology of asthma via the robust production of type 2 cytokines. Recent studies have demonstrated that TLR7 (Toll-like receptor 7) signaling skews toward a type 1 inflammatory response in asthma, which may lead to the development of novel treatment strategies. However, the effect of TLR7 signaling on ILC2-dependent nonallergic eosinophilic inflammation remains unclear. In this study, we investigated the effects of R848, a TLR7 agonist, in a mouse model of IL-33–induced eosinophilic airway inflammation. Intranasal administration of R848 decreased infiltration of airway eosinophils and ILC2s, mucus production in epithelial cells, and type 2 cytokine production. Flow cytometric analysis identified an increased number of interstitial macrophages (IMs) expressing a high level of TLR7 in the lung upon IL-33 stimulation. IL-33–induced IMs also expressed high levels of alternatively activated (M2)-type genes and chemokines (CCL17 and CCL24). However, R848 stimulation modified these gene expressions and elicited the production of IL-27. Coculture experiments revealed that IL-33–induced IMs directly suppressed ILC2 activation in response to R848. In addition, the inhibitory effects of R848 on ILC2-induced type 2 inflammation were defective in WSX-1–deficient mice lacking the IL-27 receptor. Taken together, these findings indicate that R848 stimulates IL-33–induced IMs to suppress ILC2-mediated type 2 airway inflammation via IL-27. These findings highlight the therapeutic potential of TLR7 agonists and/or IL-27 cascades in nonallergic asthma.