Published papers

A prenatal second-hit genetic change that occurs on the wild-type allele in an embryo with a congenital pathogenic variant allele results in mosaicism of monoallelic and biallelic defect of the gene, which is called superimposed mosaicism. Superimposed mosaicism of Hailey-Hailey disease (HHD) has been demonstrated in one familial case. Here, we report two unrelated HHD cases with superimposed mosaicism: a congenital monoallelic pathogenic variant of ATP2C1, followed by a postzygotic copy-neutral loss of heterozygosity. Uniquely, neither patient had a family history of HHD at the time of presentation. In the first case, the congenital pathogenic variant had occurred de novo. In the second case, the father had the pathogenic variant but had not yet developed skin symptoms. Our cases showed that superimposed mosaicism in HHD can lack a family history and that genetic analysis is crucial to classify the type of mosaicism and evaluate the risk of familial occurrence.

＜文献概要＞症例のポイント　・頭部全体に及ぶ皮膚病変を呈した頭部血管肉腫に対し,一次治療としてドセタキセル・ゲムシタビン併用療法を用いた化学放射線療法を施行した.・主な有害事象は血液毒性で,grade 3の好中球減少と,grade 2の貧血がみられた.・6サイクル施行後,皮膚病変は脱色素斑となり,長期にわたり局所再発や転移なく経過した.

＜文献概要＞症例のポイント　・各種治療に抵抗性の30年来の関節リウマチの患者に,手指爪囲の紫斑や血疱が出現し,病理組織像で真皮小血管の閉塞像が確認されたことからBywaters' lesions(BL)と診断した.・治療経過中,関節リウマチの血清抗体価上昇および関節症状・関節外症状の出現など関節リウマチが増悪するたびにBLが出現する傾向がみられた.・関節リウマチ患者においてBLを認めた際には,病勢増悪や血管炎を疑わせる症状の有無に注意して,慎重に経過を追うことが大切である.

＜文献概要＞症例のポイント　・天疱瘡の長期寛解後に水疱性類天疱瘡(bullous pemphigoid:BP)とネフローゼ症候群を発症し,またその罹患後に間質性肺炎で死亡した1例を報告した.・同一患者に,2種類の自己免疫性水疱症が時を経て発症した.またネフローゼ症候群,間質性肺炎の発症メカニズムに,水疱性類天疱瘡と共通した自己免疫反応の存在が示唆された.詳細な関連や機構については不明な点が多く,今後のさらなる症例の蓄積が必要である.

＜文献概要＞症例のポイント　・53歳女.高校生ごろからざ瘡が多発し,頸部から体幹,四肢にかけて大小の嚢胞性皮下腫瘤が散在.腋窩・鼠径部に瘻孔を形成,排膿を繰り返していた.・本人および妹に家族性化膿性汗腺炎/familial acne inversaの病原性変異として報告されているNCSTNのナンセンス変異を同定した.・家族性化膿性汗腺炎/familial acne inversaは常染色体優性遺伝のため,次世代に遺伝する確率は50%である.妹には未成年の子どもが3人いるが,未発症未成年の遺伝学的検査は本人が成人してから本人の意思で施行するのが原則である.

＜文献概要＞症例のポイント　・PORCNの片アレル欠失によって発症した,Goltz症候群の母子例を報告した.母は生下時から両側の広大な範囲に皮疹を認めた一方で,娘は片側のごく限られた範囲にのみ皮疹を認めた.・母子間でGoltz症候群の皮疹の分布範囲が大きく異なった原因として,ランダムにおこったX染色体不活化の結果,皮膚組織において正常なPORCNを発現せず病変部をつくる細胞の割合に差があったと考えられた.PORCNに遺伝学的変化を有する場合でも,皮疹の範囲は発生初期におこるX染色体不活化の結果をそのまま反映することが示唆され,次子が同疾患に罹患した場合は姉妹間でも皮疹の範囲が大きく異なる可能性があることを両親に伝えた.

＜文献概要＞45歳,男性。左拇指爪甲の爪半月から爪甲遠位端まで伸びる幅2mmの紅色線条がみられた。爪甲遠位端には爪甲下に角質の付着を認め,同部位に非常に強い圧痛の訴えがあった。ダーモスコピーでは爪甲の下面が軽度陥凹しており,陥凹部では角質塊がみられた。紅色線条をすべて切除したところ,病理では紅色線条部の爪甲の低形成に加えて,爪床表皮の乳頭状増殖と真皮浅層の毛細血管拡張の所見を認めた。臨床および病理所見より,爪乳頭腫と診断した。術後速やかに疼痛は消失し,明らかな爪甲の変形も残さなかった。爪甲紅色線条を呈する疾患はいくつか知られており,そのひとつが爪乳頭腫である。爪乳頭腫はその病因や病態が未だ不明なこともあり,貴重な症例と考え報告した。

＜文献概要＞60歳,男性.ワルファリンカリウム内服中.初診1ヵ月前に左足外顆の皮下腫瘤を自覚した.初診2週間前に近医を受診し,ガングリオン疑いで穿刺された.その後,皮下腫瘤は増大傾向となり,疼痛も出現したため前医整形外科を受診した.MRIにて陳旧性血腫を認め,当科紹介受診した.初診時,左足外顆に径5cm大,びらんを伴う暗紫紅色の皮下腫瘤を認め,発赤と腫脹を伴っていた.造影CTで活動性出血を示唆する所見なく,皮下血腫の二次感染を疑い抗生剤投与と圧迫療法を開始したが増悪傾向で第7病日に局所麻酔下で血腫除去術を施行した.術中,深部動脈からの活動性出血を認め結紮処理した.脂肪組織と筋膜の間に血腫を生じており,自験例をdeep dissecting hematomaと診断した.血腫が出血源を圧迫していたため出血が持続的ながら緩徐であり,画像検査で活動性出血を同定できなかったと考えられた.臨床的に血腫の拡大を疑う場合は,画像所見にかかわらず早期の外科的治療介入が重要と考えた.

Annular erythema is one of the cutaneous manifestations of Sjögren’s syndrome (SS). Topical corticosteroids and tacrolimus, and oral corticosteroids, have been used as treatments for this condition. However, the safety and efficacy of these treatments remains unsatisfactory, and further development of therapies are desired. In this study, we performed a retrospective analysis of 16 annular erythema associated with SS (AESS) patients treated with hydroxychloroquine (HCQ). Disease activity was assessed using a modified version of the Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI), which we termed the modified CLASI (m-CLASI). HCQ treatment improved AESS lesions in all 16 patients. The mean m-CLASI score was reduced by 85.6% at the 12-week follow-up relative to baseline (p < 0.01). Notably, 60% (6/10 cases) of patients with AESS lesions limited to the facial area achieved complete remission within 4 weeks. In the analysis of six patients who had taken oral prednisolone before starting HCQ, all were able to reduce the dose within 52 weeks without relapse. Particularly, 75% (3/4 cases) of patients with prednisolone dose of more than 5 mg/day could reduce their dose to less than 5 mg/day in combination with HCQ. For the safety concerns, two patients experienced grade 1 diarrhea during the 52-week observation period. However, neither serious adverse events nor adverse events requiring discontinuation of treatment occurred. The results of the present study suggest that HCQ may not only be highly effective as a single agent, but may also be useful as a steroid-sparing agent in refractory case requiring long-term steroid administration, making it a good treatment option for AESS.

Loss-of-function mutations of filaggrin (FLG) gene (FLG) are the strongest known genetic risk factor for atopic dermatitis (AD). It is still debatable how FLG gene mutations and the resulting abnormal amount of FLG protein contribute to skin barrier function and symptoms of AD. In this study, we examined the effects of loss-of-function mutations of FLG gene on the severity of skin lesions and skin barrier function in 55 patients with AD by evaluating eight patients with AD with FLG gene mutations and 47 patients with AD without mutations. The results showed that the FLG gene mutation did not affect the duration of AD, severity of AD, degree of local inflammatory symptoms, skin water content and trans-epidermal water loss of the lesions. Next, in these eight mutation carriers and the 47 non-carriers, stratum corneum was collected from the three site of skin lesions using tape-stripping method, and the amounts of FLG protein and total amino acid contained in the stratum corneum was measured to investigate the effect of the FLG gene mutation on the amount of FLG gene product in the local lesion. FLG abnormalities had little effect on FLG protein and total amino acid content in the stratum corneum in the lesional skin. The amount of the FLG products, especially amino acids derived from FLG, in the stratum corneum of AD lesional skin is influenced by development of dermatitis. The results obtained from this study supports that the activation of Th2-dominant inflammatory cells, together with FLG abnormality, plays a role in suppressing the production of FLG in skin lesions.

The transepidermal water loss has been widely used as a method for directly evaluating the barrier function of the stratum corneum of the skin. However, transepidermal water loss could not be measured continuously for a long period of time, and there were no reports of continuous monitoring of skin barrier functions. Here, a method is reported to continuously monitor the skin electrical resistance by nanomesh electrodes for a long period of time while maintaining the natural skin condition that does not inhibit water evaporation. Simultaneous measurements of the skin electrical resistance by nanomesh electrodes and transepidermal water loss exhibits a linear fit with a high negative correlation. Furthermore, dynamics of skin physiological functions are successfully visualized by monitoring of the skin electrical resistance by nanomesh electrodes for 30 h in daily life.

SARS-CoV-2 whole-genome sequencing of samples from COVID-19 patients is useful for informing infection control. Datasets of these genomes assembled from multiple hospitals can give critical clues to regional or national trends in infection. Herein, we report a lineage summary based on data collected from hospitals located in the Tokyo metropolitan area. We performed SARS-CoV-2 whole-genome sequencing of specimens from 198 patients with COVID-19 at 13 collaborating hospitals located in the Kanto region. Phylogenetic analysis and fingerprinting of the nucleotide substitutions were performed to differentiate and classify the viral lineages. More than 90% of the identified strains belonged to Clade 20B, which has been prevalent in European countries since March 2020. Only two lineages (B.1.1.284 and B.1.1.214) were found to be predominant in Japan. However, one sample from a COVID-19 patient admitted to a hospital in the Kanto region in November 2020 belonged to the B.1.346 lineage of Clade 20C, which has been prevalent in the western United States since November 2020. The patient had no history of overseas travel or any known contact with anyone who had travelled abroad. Consequently, the Clade 20C strain belonging to the B.1.346 lineage appeared likely to have been imported from the western United States to Japan across the strict quarantine barrier. B.1.1.284 and B.1.1.214 lineages were found to be predominant in the Kanto region, but a single case of the B.1.346 lineage of clade 20C, probably imported from the western United States, was also identified. These results illustrate that a de-centralized network of hospitals offers significant advantages as a highly responsive system for monitor-ing regional molecular epidemiologic trends.

Pemphigus vulgaris is an autoimmune blistering disease caused by IgG targeting desmoglein 3 (Dsg3), an adhesion molecule of keratinocytes. Anti-Dsg3 IgG production is prevented in healthy individuals, but it is unclear how Dsg3-specific B cells are regulated. To clarify the immunological condition regulating Dsg3-specific B cells, a pathogenic anti-Dsg3 Ig (AK23) knock-in mouse was generated. AK23 knock-in B cells developed normally without undergoing deletion or acquiring an anergic phenotype in vivo. The knock-in B cells showed Ca2+ influx upon IgM cross-linking and differentiated into AK23-IgG+ B cells after LPS and IL-4 stimulation in vitro that induced a pemphigus phenotype after adoptive transfer into Rag2-/- mice. However, the knock-in mouse itself produced AK23-IgM but little IgG without blisters in vivo. Dsg3 immunization and skin inflammation caused AK23-IgG production and a pemphigus phenotype in vivo. Furthermore, Fcgr2b deficiency or haploinsufficiency spontaneously induced AK23-IgG production and a pemphigus phenotype with poor survival rates in AK23 knock-in mice. To assess Fcgr2b involvement in Ig class-switch efficiency, postswitch transcripts of B cells were quantified and significantly higher in Fcgr2b-/- and Fcgr2b1/mice than wild-type mice in a gene dose-dependent manner. Finally, RNA sequencing revealed reduced expression of FCGR2B and FcγRIIB-related genes in patient B cells. These results indicated that Dsg3-specific B cells do not spontaneously perform pathogenic class switching in vivo, and pemphigus phenotype induction was prevented under normal conditions. Attenuated FcγRIIB signaling is also one of the drivers for pathogenic class switching and is consistent with immunological features identified from clinical samples. This study unveiled a characteristic immune state silencing autoreactive B cells in mice.

Introduction:Genetic alterations of KIT gene are known to be one of the major causes of melanoma. Those are more common in the mucous and acral subtypes and KIT is regarded as major oncogene in Asian melanomas, where the prevalence of these subtypes is high. Up to date, several clinical trials have been conducted to target KIT gene alterations in melanoma with unsatisfied efficacies. Imatinib mesylate, a small-molecule inhibitor of the KIT tyrosine kinase, provides a rapid but not durable clinical response in KIT-mutant melanoma. Meanwhile, recent basic and clinical evidence have revealed another aspect of KIT-targeted therapy, namely the enhancement of antitumor activity of immune checkpoint inhibitors. Herein, we designed clinical trial of co-administrating imatinib mesylate and pembrolizumab (anti-PD-1 antibody) to evaluate its safety and efficacy.Methods and analysis:This is an open-label, single-arm, phase I/II clinical trial involving Japanese patients with metastatic KIT-mutant melanoma that are refractory to standard therapy including anti-PD-1 therapy. Phase I study is a dose-escalation study comprising two dose levels of imatinib mesylate (200 and 400 mg/day, respectively) with fixed dose of pembrolizumab (200 mg every 3 weeks) to evaluate safety and tolerability and determine recommended phase II dose. The primary endpoint of the phase II study is the objective response rate after 4 cycles (3 weeks/cycle) of pembrolizumab and imatinib mesylate at the dose determined in phase I, based on RECIST version 1.1. A Simon's minimax two-stage design is employed to test the null hypothesis of a 5% response rate vs 30% alternative, which will be rejected when a lower confidence limit of two-sided 90% confidence interval of true response rate is over than threshold response rate. The secondary endpoints include progression free survival, overall survival, best overall response and incidence of adverse events. Totally, a target size of 22 patients will be expected.Discussion:If this study shows efficacy and acceptable safety profile, it will contribute to the development of novel treatment option for patients with KIT-mutant melanoma that are refractory to standard therapy.Trial registration:NCT04546074. Date of Registration: September 11, 2020 (https://clinicaltrials.gov/ct2/show/NCT04546074). Date of First Participant Enrollment: December 23, 2020.

While bulk water and hydration water coexist in cells to support the expression of biological macromolecules, how the dynamics of water molecules, which have long been only a minor role in molecular biology research, relate to changes in cellular states such as cell death has hardly been explored so far due to the lack of evaluation techniques. In this study, we developed a high-preci-sion measurement system that can discriminate bulk water content changes of ±0.02% (0.2 mg/cm3) with single-cell-level spatial resolution based on a near-field CMOS dielectric sensor operating at 65 GHz. We applied this system to evaluate the temporal changes in the bulk water content during the cell death process of keratinocytes, called corneoptosis, using isolated SG1 (first layer of stratum granulosum) cells in vitro. A significant irreversible increase in the bulk water content was observed approximately 1 h before membrane disruption during corneoptosis, which starts with cytoplasmic high Ca2+ signal. These findings suggest that the calcium flux may have a role in triggering the increase in the bulk water content in SG1 cells. Thus, our near-field CMOS dielectric sensor provides a valuable tool to dissect the involvement of water molecules in the various events that occur in the cell.

Intravenous Ig (IVIG) is a treatment option for intractable cases of pemphigus vulgaris (PV), an autoimmune blistering disease caused by autoantibodies against desmoglein 3 (DSG3). To investigate the efficacy of IVIG on autoantibody secretion, we produced PV model mice by adoptive transfer of immunized Dsg3−/− splenocytes to Rag2−/− mice. We found that circulating anti-DSG3 IgG ELISA titer decreased in PV model mice after 5 days of treatment with IVIG compared with PBS-treated mice, whereas the F(ab’)2 fragment did not suppress the anti-DSG3 IgG titer. enzyme-linked immunospot assay revealed that IVIG treatment reduced the frequency of anti-DSG3 antibody–secreting cells in the spleen but not in lymph nodes and bone marrow. Moreover, this reduction was observed only in the splenic B220− fraction but not in the B220+ fraction. Furthermore, IVIG decreased the serum levels of anti-DSG3 IgG, even after a significant reduction of its titer, owing to antibody-mediated CD20+ B cell depletion. In addition, IVIG suppressed anti-DSG3 IgG production in B220−CD138+ plasma cells derived from PV model mice ex vivo. These results indicate that IVIG reduced autoantibody production in B220− cells containing plasma cells in PV model mice, and this function may indicate one of the mechanisms of action of IVIG on PV.

TMEM79 is a predisposing gene for atopic dermatitis. Tmem79-deficient mice develop spontaneous dermatitis in a biphasic pattern. The first-phase dermatitis is unique because it occurs independent of microbiota status, whereas the second-phase dermatitis is microbiota dependent. In this study, we sought to identify the key factors mediating the development of first-phase dermatitis. Structural analysis showed that sebaceous gland hyperplasia started from first-phase dermatitis. Longitudinal RNA sequencing analysis revealed significant activation of fatty acid lipid metabolism pathways in first-phase dermatitis, whereas T helper 17‒based immune response genes were highly expressed in second-phase dermatitis. Quantitative RT-PCR analysis revealed that genes involved in fatty acid elongation and sebocyte differentiation were upregulated in first-phase dermatitis. The results of thin-layer chromatography supported these findings with an increased abundance of wax esters, cholesterol esters, and fatty alcohols in hair lipids. Further gas chromatography-tandem mass spectrometry analysis showed an increase in total fatty acid production, including that of elongated C20–24 saturated and C18–24 monounsaturated fatty acids. Collectively, these results suggest that aberrant production of sebaceous long-chain fatty acids is associated with microbiota-independent dermatitis. Further investigation of Tmem79-deficient mice may clarify the role of certain fatty acids in dermatitis.

Importance: Neonatal linear immunoglobulin A (IgA) bullous dermatosis (LABD) is a rare disease that can be fatal when associated with respiratory failure. All previously reported cases of neonatal LABD have been in newborns with healthy asymptomatic mothers, and the pathogenic IgA was of unknown origin. Objective: To clarify the origin of IgA associated with LABD in neonates born of healthy asymptomatic mothers. Design, Setting, and Participants: This case study analyzed the laboratory findings of a single breast-fed newborn male with neonatal LABD admitted to the Keio University Hospital in Tokyo and his healthy asymptomatic mother. The healthy newborn developed life-threatening blisters and erosions of the skin and mucous membranes on day 4 after birth. Blood serum, skin, and maternal breast milk were examined for IgA autoantibodies. Main Outcomes and Measures: Histopathologic and immunofluorescence analyses of specimens (serum, skin, and breast milk) from the patient and his mother. Results: Histopathologic evaluation of the newborn's skin revealed subepidermal blisters with neutrophil infiltrates, and immunofluorescence testing showed linear IgA deposition along the basement membrane zone (BMZ), which lead to the diagnosis of neonatal LABD. Indirect immunofluorescence using normal human skin after treatment with 1-mol/L sodium chloride showed the patient to have circulating IgA binding to the dermal side of BMZ. Immunohistochemical staining proved the deposition of secretory IgA in the neonatal skin by demonstrating the presence of J chain - not been seen in other LABD cases - indicating that the autoantibodies producing the blisters were derived from the maternal breast milk. Although no circulating IgA against the skin was detected in mother's sera, the breast milk contained IgA that reacted with the dermal side of the BMZ. No new blister formation was observed after cessation of breastfeeding. Conclusions and Relevance: The results of this case study suggest a passive transfer of pathogenic IgA to a newborn from an asymptomatic mother via breast milk. In prior reports, no serum from asymptomatic mothers of newborns with LABD had IgA autoantibodies binding to skin components; however, in this case, we found that the maternal breast milk contained IgA autoantibodies associated with neonatal LABD. In neonatal LABD, maternal breast milk should be examined for IgA autoantibodies and breast milk feeding should be discontinued as soon as neonatal LABD is suspected..

Pierre-Robin sequence (PRS) is a rare, congenital defect presenting with micrognathia, glossoptosis, and airway obstruction with variable inclusion of a cleft palate. Overlapping PRS with neurofibromatosis type 2 (NF2) is a syndrome caused by a chromosome 22q12 microdeletion including NF2. We describe a patient with severe early-onset NF2 overlapping with PRS that showed micrognathia, glossoptosis, and a mild form of cleft palate. We detected a de novo chromosome 22q12 microdeletion including MN1 and NF2 in the patient. Previous cases of overlapping PRS and NF2 caused by the chromosome 22q12 microdeletions showed severe NF2 phenotypes with variable severity of cleft palate and microdeletions of varying sizes. Genotype-phenotype correlations and comparison of the size and breakpoint of microdeletions suggest that some modifier genes distal to MN1 and NF2 might be linked to the cleft palate severity.