Bullous pemphigoid (BP) is by far the most common autoimmune blistering dermatosis that mainly occurs in the elderly. The BP180 is a transmembrane glycoprotein, which is highly immunodominant in BP. The structure and location of BP180 indicate that it is a significant autoantigen and plays a key role in blister formation. Autoantibodies from BP patients react with BP180, which leads to its degradation and this has been regarded as the central event in BP pathogenesis. The consequent blister formation involves the activation of complement-dependent or -independent signals, as well as inflammatory pathways induced by BP180/anti-BP180 autoantibody interaction. As a multi-epitope molecule, BP180 can cause dermal–epidermal separation via combining each epitope with specific immunoglobulin, which also facilitates blister formation. In addition, some inflammatory factors can directly deplete BP180, thereby leading to fragility of the dermal–epidermal junction and blister formation. This review summarizes recent investigations on the role of BP180 in BP pathogenesis to determine the potential targets for the treatment of patients with BP.

TWEAK participates in various cellular effects by engaging its receptor of Fn14. Increased levels of soluble TWEAK are associated with systemic autoimmunity in patients with lupus erythematosus, rheumatoid arthritis, or dermatomyositis. However, the role of TWEAK in bullous pemphigoid (BP) remains unknown. In this study, we found an elevated serum level of TWEAK and a positive correlation between serum TWEAK and anti-BP180 antibodies. Immunohistochemistry showed strong TWEAK and Fn14 expression and implied an opposite relationship between the TWEAK and BP180 expression in skin samples from BP patients. In vitro TWEAK stimuli reduced BP180 expression in HaCaT cells and inhibited the adhesion of cells to the culture dish. Consistently, the transfection of Fn14 small interfering RNA preserved BP180 and protected cells from losing adherence. Moreover, such effect of TWEAK correlated with activation of the extracellular signal-regulated kinase and NF-κB pathways and downstream ADAMs. By silencing ADAM17 with small interfering RNA, we showed that ADAM17 participated in TWEAK-induced BP180 loss. Therefore, TWEAK may contribute to the pathogenesis of BP by reducing BP180 expression and cellular adherence, involving the activation of ERK and NF-κB pathways. TWEAK may serve as a biomarker or therapeutic target of BP.

Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) binds to its sole receptor fibroblast growth factor-inducible 14 (Fn14), participating in various inflammatory responses. Recently, TWEAK/Fn14 activation was found prominent in the lesions of cutaneous lupus erythematosus (CLE). This study was designed to further reveal the potential role of this pathway in Ro52-mediated photosensitization. TWEAK, Fn14, and Ro52 were determined in the skin lesions of patients with CLE. Murine keratinocytes received ultraviolet B (UVB) irradiation or plus TWEAK stimulation and underwent detection for Ro52 and proinflammatory cytokines. The chemotaxis of J774.2 macrophages was evaluated on TWEAK stimulation of cocultured keratinocytes. We found that TWEAK, Fn14, and downstream cytokines were highly expressed in CLE lesions that overexpressed Ro52. Moreover, TWEAK enhanced the UVB-induced Ro52 upregulation in murine keratinocytes. Meanwhile, TWEAK stimulation of keratinocytes favored the migration of macrophages through promoting the production of chemokine C–C motif ligands 17 and 22. Furthermore, Fn14 siRNA transfection or nuclear factor-kappa B (NF-κB) inhibitor abrogated the TWEAK enhancement of Ro52 expression in keratinocytes. Similarly, TNF receptor associated factor 2 (TRAF2) siRNA reduced the protein level of Ro52 in these cells upon TWEAK stimulation. Interestingly, UVB irradiation increased the expression of TNF receptor type 1 (TNFR1) but not affecting TNFR2 expression in keratinocytes. In conclusion, the TWEAK/Fn14 signaling participates in Ro52-mediated photosensitization and involves the activation of NF-κB pathway as well as the function of the TRAF2/TNFR partners.

Inflammatory conditions represent the largest class of chronic skin disease, but the molecular dysregulation underlying many individual cases remains unclear. Single-cell RNA sequencing (scRNA-seq) has increased precision in dissecting the complex mixture of immune and stromal cell perturbations in inflammatory skin disease states. We single-cell–profiled CD45 + immune cell transcriptomes from skin samples of 31 patients (7 atopic dermatitis, 8 psoriasis vulgaris, 2 lichen planus (LP), 1 bullous pemphigoid (BP), 6 clinical/histopathologically indeterminate rashes, and 7 healthy controls). Our data revealed active proliferative expansion of the T reg and Trm components and universal T cell exhaustion in human rashes, with a relative attenuation of antigen-presenting cells. Skin-resident memory T cells showed the greatest transcriptional dysregulation in both atopic dermatitis and psoriasis, whereas atopic dermatitis also demonstrated recurrent abnormalities in ILC and CD8 + cytotoxic lymphocytes. Transcript signatures differentiating these rash types included genes previously implicated in T helper cell (T H 2)/T H 17 diatheses, segregated in unbiased functional networks, and accurately identified disease class in untrained validation data sets. These gene signatures were able to classify clinicopathologically ambiguous rashes with diagnoses consistent with therapeutic response. Thus, we have defined major classes of human inflammatory skin disease at the molecular level and described a quantitative method to classify indeterminate instances of pathologic inflammation. To make this approach accessible to the scientific community, we created a proof-of-principle web interface (RashX), where scientists and clinicians can visualize their patient-level rash scRNA-seq–derived data in the context of our T H 2/T H 17 transcriptional framework.

The immunological features that distinguish COVID-19-associated acute respiratory distress syndrome (ARDS) from other causes of ARDS are incompletely understood. Here, we report the results of comparative lower respiratory tract transcriptional profiling of tracheal aspirate from 52 critically ill patients with ARDS from COVID-19 or from other etiologies, as well as controls without ARDS. In contrast to a “cytokine storm,” we observe reduced proinflammatory gene expression in COVID-19 ARDS when compared to ARDS due to other causes. COVID-19 ARDS is characterized by a dysregulated host response with increased PTEN signaling and elevated expression of genes with non-canonical roles in inflammation and immunity. In silico analysis of gene expression identifies several candidate drugs that may modulate gene expression in COVID-19 ARDS, including dexamethasone and granulocyte colony stimulating factor. Compared to ARDS due to other types of viral pneumonia, COVID-19 is characterized by impaired interferon-stimulated gene (ISG) expression. The relationship between SARS-CoV-2 viral load and expression of ISGs is decoupled in patients with COVID-19 ARDS when compared to patients with mild COVID-19. In summary, assessment of host gene expression in the lower airways of patients reveals distinct immunological features of COVID-19 ARDS.

BackgroundThe Dermatology Life Quality Index (DLQI) is the most widely used measure of health-related quality of life (HRQoL) associated with skin disease. Recently, the psychometric properties of the DLQI have caused some controversy because the instrument appears not to meet the requirements of modern test theory. The purpose of this study was to assess whether these psychometric issues also occur in Chinese patients with neurodermatitis.MethodsOne hundred fifty consecutive outpatients (83 males and 67 females) seeking treatment for neurodermatitis were assessed for eligibility for this prospective study between July 1, 2011 and September 30, 2011. The DLQI and a demographic questionnaire were completed. One female participant who incompletely answered the DLQI was excluded. Data were analyzed using the Rasch model in order to obtain meaningful scores for the DLQI. Scale assessment included analysis of rating scale function, item fit to the Rasch model, aspects of person-response validity, unidimensionality, person-separation reliability, and differential item function.ResultsThe rating scale advanced monotonically for all items in the DLQI, but item 9 did not demonstrate acceptable goodness-of-fit (Infit MnSq values >1.3) to the Rasch model. The 10 items of the DLQI met the criteria for person-separation reliability (PSI = 2.38) and the first latent dimension (general QoL) accounted for 50.8 % of the variance; but the variance explained by the second dimension (7.1 %) exceeded the criterion of 5 %. There were also limitations related to person-response validity, because ≥ 5 % (18.1 %) of cases demonstrated unacceptable fit. There was no uniform differential item functioning.ConclusionsFor neurodermatitis patients, the DLQI seems to have poor fit to the Rasch model; therefore, we recommend against using this instrument with neurodermatitis patients.

Summary Inflammatory response heterogeneity has impeded high-resolution dissection of diverse immune cell populations during activation. We characterize mouse cutaneous immune cells by single-cell RNA sequencing, after inducing inflammation using imiquimod and oxazolone dermatitis models. We identify 13 CD45 + subpopulations, which broadly represent most functionally characterized immune cell types. Oxazolone pervasively upregulates Jak2 / Stat3 expression across T cells and antigen-presenting cells (APCs). Oxazolone also induces Il4 / Il13 expression in newly infiltrating basophils, and Il4ra and Ccl24, most prominently in APCs. In contrast, imiquimod broadly upregulates Il17 / Il22 and Ccl4 / Ccl5 . A comparative analysis of single-cell inflammatory transcriptional responses reveals that APC response to oxazolone is tightly restricted by cell identity, whereas imiquimod enforces shared programs on multiple APC populations in parallel. These global molecular patterns not only contrast immune responses on a systems level but also suggest that the mechanisms of new sources of inflammation can eventually be deduced by comparison to known signatures.

TWEAK acts by engaging with Fn14 to regulate inflammatory responses, fibrosis, and tissue remodeling, which are central in the repair processes of wounds. This study aims to explore the potential role of the TWEAK/Fn14 pathway in the healing of cutaneous burn wounds. Third-degree burns were introduced in wild-type and Fn14-deficient BALB/c mice, followed by evaluation of wound areas and histological changes. The downstream cytokines including growth factors were also examined in lesional skin. Moreover, human dermal microvascular endothelial cells and dermal fibroblasts were analyzed in vitro upon TWEAK stimulation. The healing of burn wounds was delayed in Fn14-deficient mice and was accompanied by the suppression of inflammatory responses, growth factor production, and extracellular matrix synthesis. Moreover, TWEAK/Fn14 activation enhanced the migration and cytokine production of both dermal microvascular endothelial cells and dermal fibroblasts. TWEAK also facilitates the expression of α-SMA and palladin in dermal fibroblasts. Furthermore, transfection of Fn14 small interfering RNA abrogated such promotion effect of TWEAK on these cells. In conclusion, TWEAK/Fn14 signals mediate the healing of burn wounds, possibly involving TWEAK regulation of the function of resident cells.