- Atopic dermatitis (AD) affects up to 20% of children and adults worldwide. To gain a deeper understanding of the pathophysiology of AD, we conducted a large-scale transcriptomic study of AD with deeply sequenced RNA-sequencing samples using long (126-bp) paired-end reads. In addition to the comparisons against previous transcriptomic studies, we conducted in-depth analysis to obtain a high-resolution view of the global architecture of the AD transcriptome and contrasted it with that of psoriasis from the same cohort.
- Psoriasis lesions are rich in IL-17–producing T cells as well as neutrophils, which release webs of DNA-protein complexes known as neutrophil extracellular traps (NETs). Because we and others have observed increased NETosis in psoriatic lesions, we hypothesized that NETs contribute to increased T helper type 17 (Th17) cells in psoriasis. After stimulating peripheral blood mononuclear cells with anti-CD3/CD28 beads for 7 days, we found significantly higher percentages of CD3+CD4+IL-17+ (Th17) cells in the presence versus absence of NETs, as assessed by flow cytometry, IL-17 ELISA, and IL17A/F and RORC mRNAs.
- Psoriasis is a chronic disorder characterized by cutaneous and systemic manifestations. Epidemiological studies have reported increased comorbidity of psoriasis with numerous complex diseases such as metabolic clinical measurements (Greb et al., 2016; Naito and Imafuku, 2016). However, interpretation of the comorbidity remains controversial to date, because causal inference between correlated phenotypes is difficult when depending solely on epidemiological studies. Identification of causal inference between correlated phenotypes has significant clinical impacts, because modification of the causal phenotypes could benefit treatment of the outcome phenotypes.
- Terminally differentiating epidermal keratinocytes express a large number of structural and antimicrobial proteins that are involved in the physical barrier function of the stratum corneum and provide innate cutaneous host defense. Late cornified envelope (LCE) genes, located in the epidermal differentiation complex on chromosome 1, encode a family of 18 proteins of unknown function, whose expression is largely restricted to epidermis. Deletion of two members, LCE3B and LCE3C (LCE3B/C-del), is a widely-replicated psoriasis risk factor that interacts with the major psoriasis-psoriasis risk gene HLA-C*06.
- miR-146a inhibits inflammatory responses in human keratinocytes and in different mouse models of skin inflammation. Little is known about the role of miR-146b in the skin. In this study, we confirmed the increased expression of miR-146a and miR-146b (miR-146a/b) in the lesional skin of patients with psoriasis. The expression of miR-146a was approximately twofold higher than that of miR-146b in healthy human skin, and it was more strongly induced by stimulation of proinflammatory cytokines in keratinocytes and fibroblasts.
- The factors involved in maintaining a localized inflammatory state in psoriatic skin remain poorly understood. Here, we demonstrate through metabolomic and transcriptomic profiling marked suppression of glucocorticoid biosynthesis in the epidermis of psoriatic skin leading to localized deficiency of cortisol. Utilizing a 3D human epidermis model, we demonstrate that glucocorticoid biosynthesis is suppressed by proinflammatory cytokines and that glucocorticoid deficiency promotes inflammatory responses in keratinocytes.