Comprehensive Genomic Characterization of Staphylococcus aureus Isolated from Atopic Dermatitis Patients in Japan: Correlations with Disease Severity, Eruption Type, and Anatomical Site.

Atopic dermatitis (AD) shows frequent recurrence. Staphylococcus aureus is the primary microbial component in AD and is associated with disease activity. However, traditional typing methods have failed to characterize virulent AD isolates at the clone level. We conducted a comprehensive genomic characterization of S. aureus strains isolated from the skin of AD patients and healthy donors, comparing the whole-genome sequences of the 261 isolates with anatomical and lesional (AD-A)/nonlesional (AD-NL)/healthy sites, eruption types, clinical scores, virulence, and antimicrobial resistance gene repertoires in Japan. Sequence type (ST) diversity was lost with worsening disease activity; ST188 was the most frequently detected ST in AD-A and had the strongest correlation with AD according to the culture rate and proportion with worsening disease activity. ST188 and ST20 isolates inhabited all skin conditions, with significantly higher proportions in AD skin than in healthy skin. ST8, ST15, and ST5 proportions were equivalent for all skin conditions; ST30 was detected only in healthy skin; and ST12 was detected only in AD skin. ST97 detected in AD-A and healthy skin was clearly branched into two subclades, designated ST97A and ST97H. A comparison of two genomes led to the discovery that only ST97A possessed the complete trp operon, enabling bacterial survival without exogenous tryptophan (Trp) on AD skin, where the Trp level was significantly reduced. Primary STs showing an AD skin inhabitation trend (ST188, ST97A, ST20, and ST12) were all trp operon positive. The predominant clones (ST188 and ST97) possessed almost no enterotoxin genes, no mecA gene, and few other antimicrobial resistance genes, different from the trend observed in Europe/North America. IMPORTANCE While Staphylococcus aureus is a member of the normal human skin flora, its strong association with the onset of atopic dermatitis (AD) has been suggested. However, previous studies failed to assign specific clones relevant to disease activities. Enterotoxins produced by S. aureus have been suggested to aggravate and exacerbate the inflammation of AD skin, but their role remains ambiguous. We conducted a nuanced comprehensive characterization of isolates from AD patients and healthy donors, comparing the whole-genome sequences of the isolates with anatomical and lesional/nonlesional/healthy sites, eruption types, clinical scores, virulence, and antimicrobial resistance gene repertoires in Japan. We demonstrate that specific clones are associated with disease severity and clinical manifestations, and the dominant clones are devoid of enterotoxin genes and antimicrobial resistance genes. These findings undermine the established notion of the pathophysiological function of S. aureus associated with AD and introduce a new concept of S. aureus colonization in AD.

Single nucleotide variations in genes associated with innate immunity are enriched in Japanese adult cases of face and neck type atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is heterogenous in terms of phenotype as well as genetic and environmental factors, while its associated genetic factors and pathophysiology are not fully understood. OBJECTIVE: We identify novel genetic factors enriched in a subgroup of AD patients with characteristic clinical features. METHODS: We clinically subgrouped 18 AD patients who exhibited distinctive characteristic of persistent skin eruption areas on the face and neck from 92 Japanese adult AD patients and identified disease-associated genetic factors enriched within the subgroup. Targeted resequencing and subsequent genetic association analyses were used to identify novel enriched genetic variations in the subgroup compared with the other AD patients. RESULTS: Targeted resequencing of 648 skin associated genes revealed an enrichment of 12 single nucleotide variations (SNVs) in patients with face and neck AD (n = 18) compared with the general Japanese population in the database. Subsequent allele frequency comparison between the face and neck AD and non - face and neck AD subgroups revealed enrichment of five SNVs. Multivariate analysis using genotype data revealed that three SNVs in theTLR1, TIRAP, and PSAPL1 genes, two of the three genes are involved in the Toll-like receptor pathway, were significantly enriched in patients with face and neck AD. CONCLUSION: These findings revealed that the SNVs in genes associated with the innate immune pathway are enriched in a subgroup of AD. The combinational approach of clinical subgrouping and genotyping is valuable for detecting novel disease-associated genetic factors.

Thymoma-associated multi-organ autoimmunity: A case of graft-versus-host disease-like erythroderma complicated by Good syndrome successfully treated by thymectomy.

Thymoma-associated multi-organ autoimmunity disease (TAMA) is a rare paraneoplastic disorder, clinicopathologically similar to graft-versus-host disease (GVHD). Many reported cases follow a difficult course; half of them die from serious infectious diseases subsequent to immunosuppression induced by chemotherapy for unresectable thymoma, or intensive therapies including systemic steroids for complicating autoimmune diseases and GVHD-like symptoms. We report a patient whose skin symptoms were improved subsequently to total thymectomy. The patient also presented with hypogammaglobulinemia, which led to the diagnosis of complicated Good syndrome. Taking account of her immunodeficient condition, antibiotics and i.v. immunoglobulin were administrated promptly on onset of bacterial pneumonia, which was successfully treated. According to a review of the published work, treatments with systemic steroids for skin symptoms have limited effects and may contribute to serious infection. Our case indicates that successful treatment of thymoma itself may lead to the amelioration of the disease. The management priority should be given to the treatment of thymoma and the control of subsequent immune abnormality other than GVHD-like erythroderma.