Published papers

Coronavirus disease 2019 (COVID-19) caused by human severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a worldwide problem. From the standpoint of hospital infection control, determining the source of infection is critical. We conducted the present study to evaluate the efficacy of using whole genome sequencing to determine the source of infection in hospitalized patients who do not have a clear infectious contact history. Recently, we encountered two seemingly separate COVID-19 clusters in a tertiary hospital. Whole viral genome sequencing distinguished the two clusters according to the viral haplotype. However, the source of infection was unclear in 14 patients with COVID-19 who were clinically unlinked to clusters 1 or 2. These patients, who had no clear history of infectious contact within the hospital (‘undetermined source of infection’), had haplotypes similar to those in cluster 2 but did not have two of the mutations used to characterize cluster 2, suggesting that these 14 cases of ‘undetermined source of infection’ were not derived from cluster 2. Whole viral genome sequencing can be useful for confirming that sporadic COVID-19 cases with an undetermined source of infection are indeed not part of clusters at the institutional level.

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.

The skin serves as the interface between the human body and the environment and interacts with the microbial community. The skin microbiota consists of microorganisms, such as bacteria, fungi, mites, and viruses, and they fluctuate depending on the microenvironment defined by anatomical location and physiological function. The balance of interactions between the host and microbiota plays a pivotal role in the orchestration of skin homeostasis; however, the disturbance of the balance due to an alteration in the microbial communities, namely, dysbiosis, leads to various skin disorders. Recent developments in sequencing technology have provided new insights into the structure and function of skin microbial communities. Based on high-throughput sequencing analysis, a growing body of evidence indicates that a new treatment using live bacteria, termed bacteriotherapy, is a feasible therapeutic option for cutaneous diseases caused by dysbiosis. In particular, the administration of specific bacterial strains has been investigated as an exclusionary treatment strategy against pathogens associated with chronic skin disorders, whereas the safety, efficacy, and sustainability of this therapeutic approach using isolated live bacteria need to be further explored. In this review, we summarize our current understanding of the skin microbiota, as well as therapeutic strategies using characterized strains of live bacteria for skin inflammatory diseases. The ecosystem formed by interactions between the host and skin microbial consortium is still largely unexplored; however, advances in our understanding of the function of the skin microbiota at the strain level will lead to the development of new therapeutic methods.

Autoreactive B cells are assumed to play a critical role in pemphigus; however, the characteristics of these cells are not yet fully understood. In this study, 23 pemphigus vulgaris or pemphigus foliaceus samples were used to isolate circulating desmoglein (DSG)-specific B cells. Transcriptome analysis of the samples was performed at the single-cell level to detect genes involved in disease activity. DSG1- or DSG3-specific B cells from three patients’ differentially expressed genes related to T cell costimulation (CD137L) as well as B-cell differentiation (CD9, BATF, TIMP1) and inflammation (S100A8, S100A9, CCR3), compared with nonspecific B cells from the same patients. When the DSG1-specific B cells before and after treatment transcriptomes of the patient with pemphigus foliaceus were compared, there were changes in several B-cell activation pathways not detected in non−DSG1-specific B cells. This study clarifies the transcriptomic profile of autoreactive B cells in patients with pemphigus and documents the gene expression related to disease activity. Our approach can be applied to other autoimmune diseases and has the potential for future detection of disease-specific autoimmune cells.

Background: Natto (fermented soybeans)-induced hypersensitivity is characterized by delayed symptom onset that hampers diagnosis. We aimed to clarify the clinical utility of the basophil activation test (BAT) in the diagnosis of natto-induced hypersensitivity. Methods: Five patients with a history of anaphylaxis and chronic urticaria suspected of natto-induced hypersensitivity and seven with chronic spontaneous urticaria clinically unrelated to natto were enrolled in the patient and control groups, respectively. The BAT was performed with two incubation times, 15 min and 1 h, in combination with various concentrations of natto-mucilage extract. Results: In controls, CD203c levels in basophils remained low in the 15-min incubation but were significantly increased in the 1-h incubation. In the patient group, in the 15-min condition, basophil CD203c was significantly upregulated by natto mucilage but not by soybean vs controls (P = 0.001). Low concentrations of natto mucilage were sufficient to upregulate basophil CD203c in the anaphylaxis cases, but high concentrations were required to induce the same effect in the urticaria cases. Finally, the dose-dependent pattern of the BAT results differed significantly between the anaphylaxis and urticaria cases (P = 0.006). Thus, a strong background reaction was observed in the BAT with 1 h incubation; 15 min of incubation was sufficient to identify patients with natto-induced hypersensitivity and may distinguish the clinical phenotype of natto-induced hypersensitivity, i.e., anaphylaxis or urticaria. Conclusions: The BAT with a 15-min incubation period is useful in diagnosing natto-induced hypersensitivity.

The skin is a pivotal barrier between the human body and the environment, and is a habitat for numerous microorganisms. While host–microbiota interactions in the skin are essential for homeostasis, disturbances in microbial composition and the abnormal growth of certain bacteria are associated with various diseases. Here, we identify strains and communities of skin commensals that contribute to or impair skin barrier function. Furthermore, we discuss the skin microenvironments suitable for specific microbiota that exert therapeutic effects and suggest focus areas for the prospective development of therapeutic strategies using bacterial agents. Finally, we highlight recent efforts to treat skin diseases associated with live bacteria.

OX40 is an important costimulatory molecule for T-cell expansion and survival. Because OX40 is expressed on most T-cell subsets, it is an attractive therapeutic target for a variety of T-cell‒mediated diseases. Clinical trials are already underway for some skin inflammatory diseases. In this review, we present various observations that improve our understanding of how OX40-targeted therapy can be applied for skin inflammatory diseases, such as atopic dermatitis and psoriasis, T helper (Th)2- and Th17-mediated diseases, respectively. The important OX40/OX40L-mediated interaction between T cells and other immune cells is also discussed in terms of skin autoimmune diseases, such as alopecia areata and pemphigus. Regulatory T cells (Tregs) highly express OX40, and the skin harbors a large Treg population; thus, understanding how OX40-targeted treatment acts on Tregs is vital for the development of therapeutic strategies for various skin diseases.

Background: Intestinal microinflammation with immune dysfunction due to severe acute respiratory syndrome coronavirus 2 reportedly precipitates post-infectious irritable bowel syndrome. This study aimed to elucidate potential risk factors for subsequent development of irritable bowel syndrome, hypothesizing that it is associated with specific symptoms or patient backgrounds. Methods: This single-center retrospective observational study (2020–2021) included adults with confirmed coronavirus disease requiring hospital admission and was conducted using real-world data retrieved from a hospital information system. Patient characteristics and detailed gastrointestinal symptoms were obtained and compared between patients with and without coronavirus disease-induced irritable bowel syndrome. Multivariate logistic models were used to validate the risk of developing irritable bowel syndrome. Moreover, daily gastrointestinal symptoms during hospitalization were examined in patients with irritable bowel syndrome. Results: Among the 571 eligible patients, 12 (2.1%) were diagnosed with irritable bowel syndrome following coronavirus disease. While nausea and diarrhea during hospitalization, elevated white blood cell count on admission, and intensive care unit admission were associated with the development of irritable bowel syndrome, nausea and diarrhea were identified as risk factors for its development following coronavirus disease, as revealed by the adjusted analyses (odds ratio, 4.00 [1.01–15.84] and 5.64 [1.21–26.31], respectively). Half of the patients with irritable bowel syndrome had both diarrhea and constipation until discharge, and constipation was frequently followed by diarrhea. Conclusions: While irritable bowel syndrome was rarely diagnosed following coronavirus disease, nausea and diarrhea during hospitalization precede the early signs of irritable bowel syndrome following coronavirus disease.

© 2018 The Authors Vancomycin (VCM) is known to induce linear IgA bullous dermatosis (LAD). However, in contrast to conventional LAD, in which circulating IgA autoantibodies against basement membrane proteins are commonly detected, patient sera from VCM-induced LAD yields negative results in indirect immunofluorescence microscopy, and the targeted autoantigen remains undetermined. By using sera from a typical patient with VCM-induced LAD, we identified that co-incubation of sera with VCM resulted in linear IgA deposition at the basement membrane zone by indirect immunofluorescence. Patient sera reacted with the dermal side of 1 mol/L NaCl-split skin and with the recombinant noncollagenous (i.e., NC1) domain of type VII collagen by both immunoblot and ELISA in the presence of VCM. The investigation of an additional 13 patients with VCM-induced LAD showed that 10 out of the 14 sera (71.4%) reacted with the NC1 domain of type VII collagen by ELISA when spiked with VCM, whereas only 4 (28.6%) tested positive without it. The enhancement of reactivity to NC1 by VCM, as determined by optical density via ELISA, was observed in 10 out of the 14 sera (71.4%). These findings indicate that type VII collagen is a target autoantigen in VCM-induced LAD and that VCM mediates IgA autoreactivity against type VII collagen, providing an insight into mechanisms involved in drug-induced autoimmune disease.

© 2018 Background: Centrosomes contain two centrioles: a pre-existing mature centriole and a newly formed immature centriole. Each centriole is duplicated once within a cell cycle, which is crucial for proper centrosome duplication and cell division. Objective: To describe the centrosome duplication cycle in human epidermis, Bowen's disease (BD), and squamous cell carcinoma (SCC). Methods: Immunofluorescent staining of centriolar proteins and Ki-67 was used to evaluate cell cycles and the number of centrioles. Centrobin and Outer dense fiber of sperm tails 2 (ODF2) were used as markers for immature and mature centrioles, respectively. Results: Normal human primary epidermal keratinocytes in a monolayered culture have one centrobin+ centriole (CTRB1+ cells) supposed in G0/G1 phases or have two centrobin+ centrioles (CTRB2+ cells) supposed in S−G2 phase. In a three-dimensional culture and in vivo human epidermis, the majority of suprabasal cells were CTRB2+ cells, in spite of their non-proliferative Ki-67− nature. The tumor mass of BD and SCC contained CTRB1+ cells and Ki-67+ proliferating and Ki-67− non-proliferative CTRB2+ cells. Clumping cells in BD had increased numbers of centrioles, with an approximate 1:1 to 2:1 ratio of centrobin+ to ODF2+ centrioles. Conclusions: The cell cycle arrest of suprabasal cells is distinct from the G0 arrest of monolayered epithelial cells. Tumor mass of BD and SCC contained non-proliferative cells with the characteristics of the suprabasal cells of normal epidermis. A constant ratio of the number of centrobin+ to ODF2+ centrioles indicates that multiple centrioles were induced by cell division failure rather than centriole overduplication in clumping cells.

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. The human epidermal growth factor receptor 2 (HER2) is recognized as an oncogene as well as a therapeutic target in various cancers. Certain patients with advanced extramammary Paget’s disease (EMPD) have also been reported to express HER2, which is therefore considered a therapeutic target for EMPD. However, an accurate methodology to determine HER2-positive EMPD has not been established. To assess the optimal methods for detection of HER2-positive EMPD, 73 EMPD samples were analyzed by immunohistochemical (IHC) staining, fluorescence in situ hybridization (FISH), and the HER2 testing algorithm for breast cancer of the American Society of Clinical Oncology/College of American Pathologists, which combined the results of IHC staining and FISH. The results showed discordance in the rate of positive IHC staining and FISH results. While 68.6% (24/35) of the metastatic samples showed equivocal or positive IHC staining, only 37.1% (13/35) were positive by FISH. To assess the accuracy of these methods, the degree of HER2 expression detected by each method was correlated with the staining profiles of activated downstream signaling pathways involving phosphorylated p44/42 MAPK (Thr202/Tyr204) (p-ERK1/2) and phosphorylated AKT (Ser473) (p-AKT). Among 16 lymph node metastasis samples, all HER2-positive samples as determined by the testing algorithm stained positively for both p-ERK1/2 and p-AKT. On the other hand, 10-14.3% of the samples determined by FISH or IHC showed negative staining for p-ERK1/2 and p-AKT. The results showed that combining the results of IHC and FISH according to the HER2 testing algorithm is a useful method for accurately evaluating HER2-positive EMPD.

© 2017 Japanese Dermatological Association Azathioprine (AZP) is used as a corticosteroid (CS)-sparing medication to treat autoimmune blistering diseases. In this study, we examined the efficacy of AZP and the feasibility of using AZP monotherapy (without CS) to treat pemphigus and pemphigoid. We performed a retrospective study of 10 Japanese patients (seven with pemphigus and three with pemphigoid) with mild to moderate disease activity who had been treated using AZP. The treatment efficacy was evaluated based on decreases in the disease activity scores and autoantibody titers. The results demonstrate that seven out of 10 cases (70%) were treated successfully using AZP monotherapy with no severe adverse effects. The disease activity scores of the successfully-treated patients decreased to zero after 1–37.5 months (average, 11.9) and the average disease activity scores in these cases decreased significantly at 2 months (38.2 ± 36.6%) compared with the scores of the three patients who required additional systemic CS therapy (77.5 ± 3.5%) (P < 0.05). Additionally, the autoantibody titers of five cases treated successfully using AZP decreased by half at 6 months. In conclusion, our findings suggest that AZP monotherapy is a viable treatment option for mild to moderate pemphigus and pemphigoid.

© 2018 Japanese Dermatological Association The pathological mechanisms and immunological kinetics of drug-induced hypersensitivity syndrome (DIHS), including the relevance of interleukin (IL)-6, remain unclear. We report a case of drug adverse reaction that does not fulfill the diagnostic criteria of DIHS but mimics its characteristic features. Because the patient was under anti-IL-6 therapy at the onset, some symptoms typically seen in DIHS were absent, such as fever and leukocyte count abnormalities. However, the characteristic features of DIHS were clearly observed in the subsequent course, including the repeated recurrence of skin rash, prolonged liver dysfunction and reactivation of herpes viruses. This case suggested that IL-6 role at the onset is not a main factor to determine the subsequent pathomechanism of DIHS and attention should be paid to the preceding therapy for achieving accurate diagnosis.

© 2017 The Authors The autoimmune blistering skin disease pemphigus is caused by IgG autoantibodies against desmosomal cadherins, but the precise mechanisms are in part a matter of controversial discussions. This review focuses on the currently existing models of the disease and highlights the relevance of desmoglein-specific versus nondesmoglein autoantibodies, the contribution of nonautoantibody factors, and the mechanisms leading to cell dissociation and blister formation in response to autoantibody binding. As the review brings together the majority of laboratories currently working on pemphigus pathogenesis, it aims to serve as a solid basis for further investigations for the entire field.

© 2017 Langerhans cells (LCs) are antigen-presenting cells in the epidermis whose roles in antigen-specific immune regulation remain incompletely understood. Desmoglein 3 (Dsg3) is a keratinocyte cell-cell adhesion molecule critical for epidermal integrity and an autoantigen in the autoimmune blistering disease pemphigus. Although antibody-mediated disease mechanisms in pemphigus are extensively characterized, the T cell aspect of this autoimmune disease still remains poorly understood. Herein, we utilized a mouse model of CD4+ T cell-mediated autoimmunity against Dsg3 to show that acquisition of Dsg3 and subsequent presentation to T cells by LCs depended on the C-type lectin langerin. The lack of LCs led to enhanced autoimmunity with impaired Dsg3-specific regulatory T cell expansion. LCs expressed the IL-2 receptor complex and the disruption of IL-2 signaling in LCs attenuated LC-mediated regulatory T cell expansion in vitro, demonstrating that direct IL-2 signaling shapes LC function. These data establish that LCs mediate peripheral tolerance against an epidermal autoantigen and point to langerin and IL-2 signaling pathways as attractive targets for achieving tolerogenic responses particularly in autoimmune blistering diseases such as pemphigus.

© 2018 Japan Gastroenterological Endoscopy Society. All Rights Reserved. Background and Aim: Autoimmune bullous disease (ABD) is induced by autoantibodies against cell adhesion molecules, and blistering may occur on the mucous membranes of the eyes, nose, mouth, oral cavity, laryngopharynx, and esophagus. Endoscopic prevalence and features of ABD-associated esophageal lesions are not well known. We conducted the present study to assess the endoscopic prevalence of ABD-associated mucosal lesions. Methods: Endoscopic prevalence of mucosal lesions, particularly laryngopharyngeal and esophageal lesions, was used as the primary endpoint to assess the significance of upper gastrointestinal endoscopy, and clinical and endoscopic features were secondary endpoints. Results: Of 123 ABD patients, 50.4％ had apparent oral or laryngopharyngeal lesions and 30.8％had laryngopharyngeal lesions. Esophageal lesions were detected through normal observation in 16.8％ of affected patients, whereas 40.6％ exhibited epidermolysis or blood blisters by mechanical inducement, regardless of esophageal mucosal lesion detection by normal observation. Additionally, 56.0％ exhibited the Nikolsky sign with mechanical inducement. Of the 123 patients, 29.2％ did not have exposed skin lesions. Of these patients, 77.7％ had oral cavity or laryngopharyngeal lesions, 36.1％ had esophageal lesions, and 58.3％ exhibited the Nikolsky sign on esophageal mucosa. Conclusion: It is important to determine the endoscopic characteristics and findings of ABD. ABD can be suspected from endoscopic findings.