Propionate alleviates itch in murine models of atopic dermatitis by modulating sensory TRP channels of dorsal root ganglion.

BACKGROUND: Itch is the most common symptom of atopic dermatitis (AD) and significantly decreases the quality of life. Skin microbiome is involved in AD pathogenesis, whereas its role in the regulation of itch remains elusive. In this study, we aimed to investigate the effects of skin microbial metabolite propionate on acute and chronic pruritus and to explore the mechanism. METHODS: Using various mouse models of itch, the roles of propionate were explored by behavioral tests and histopathology/immunofluorescent analysis. Primary-cultured dorsal root ganglion neurons and HEK293 cells expressing recombinant human TRP channels were utilized for in vitro calcium imaging/in vivo miniature two-photon imaging in combination with electrophysiology and molecular docking approaches for investigation of the mechanism. RESULTS: Propionate significantly alleviated itch and alloknesis in various mouse models of pruritus and AD and decreased the density of intraepidermal nerve fibers. Propionate reduced the responsiveness of dorsal root ganglion neurons to pruritogens in vitro, attenuated the hyper-excitability in sensory neurons in MC903-induced AD model, and inhibited capsaicin-evoked hTRPV1 currents (IC50 = 20.08 ± 1.11 µM) via interacting with the vanilloid binding site. Propionate also decreased the secretion of calcitonin gene-related peptide by nerves in MC903-induced AD mouse model, which further attenuated itch and skin inflammation. CONCLUSION: Our study revealed a protective effect of propionate against persistent itch through direct modulation of sensory TRP channels and neuropeptide production in neurons. Regulation of itch via the skin microbiome might be a novel strategy for the treatment of AD.

Burden of Disease; the Current Status of the Diagnosis and Management of Atopic Dermatitis in China.

Atopic dermatitis (AD) is now a global health problem and has been attracting extensive attention from both academic and public society in China. This review aimed to present the current status of the prevalence, disease burden, clinical features, diagnosis, and management of AD in China. The prevalence of AD has been increasing rapidly in China during the past decades, partially due to the increased recognition of the disease; there are still substantial amounts of over-diagnosed eczema and under-diagnosed AD. Chinese dermatologists see many AD patients with atypical manifestation, which poses a challenge to the diagnosis. The Chinese diagnostic criteria for adults and pediatric patients with AD have been proposed respectively and validated with high sensitivity and specificity. International and Chinese guidelines for management of AD have been popularized; however, there are still many practices that need verification through randomized case-control study. Dupilumab and JAK inhibitors have demonstrated favorable efficacy for AD patients in China, and a multidimensional approach is needed for selection of the patients and evaluation of the efficacy and safety. Patient education and long-term management for AD are just beginning in China, and need to be strengthened in the future.

Updated skin transcriptomic atlas depicted by reciprocal contribution of single-nucleus RNA sequencing and single-cell RNA sequencing.

BACKGROUND: Single-cell RNA sequencing (scRNA-seq) has advanced our understanding of skin biology, but its utility is restricted by the requirement of fresh samples, inadequate dissociation-induced cell loss or death, and activation during tissue digestion. Single-nucleus RNA sequencing (snRNA-seq) can use frozen, hard-to-dissociate materials, which might be a promising method to circumvent the limitations of scRNA-seq for the skin tissue. OBJECTIVE: To profile skin cells using snRNA-seq in parallel with scRNA-seq. METHODS: We performed snRNA-seq in parallel with scRNA-seq for the bisected skin sample of one person and integrated previously published scRNA-seq data for analysis. We comparatively analyzed the differences in cell proportions and gene expression between the two methods. The differentiation trajectories of keratinocytes and fibroblasts were analyzed by Slingshot analysis. RESULTS: snRNA-seq was less susceptible to contamination from mitochondrial and ribosomal RNA, and exhibited a greater capacity to detect transcription factors. snRNA-seq identified more spatially and functionally relevant keratinocyte clusters that constitute cell trajectories with expected differentiation dynamics. Novel markers, e.g., LYPD3, EMP2, and CSTB, were revealed for different differentiation stages of keratinocytes, and NFIB and GRHL1 were identified as transcription factors involving in the proliferation and functional differentiation of keratinocytes. Fibroblasts were found in a state of activation in scRNA-seq. And scRNA-seq detected a greater number of immune cells. CONCLUSIONS: We generated an updated atlas of the skin transcriptome based on the reciprocal contribution of scRNA-seq and snRNA-seq.

Peripheral blood mononuclear cell- transcriptome signatures of atopic dermatitis and prediction for the efficacy of dupilumab.

BACKGROUND: Few studies have explored transcriptome of the peripheral blood mononuclear cells (PBMCs) of atopic dermatitis (AD). Parameters for prediction of the efficacy of dupilumab in AD remain obscure. OBJECTIVE: To explore transcriptome signature of the PBMCs from Chinese AD patients and the usage in predication for the efficacy of dupilumab. METHODS: A total of 56 moderate-to-severe adult AD patients were enrolled and followed up for 16 week-dupilumab treatment. PBMCs samples were collected at baseline and 16 weeks after dupilumab treatment. Thirty-five patients were subjected to RNA-sequencing. Weighted gene co-expression network analysis (WGCNA) was used to find genes for prediction of dupilumab efficacy, which was validated in the rest 21 AD patients. Another 30 healthy individuals were enrolled and subjected to RNA-sequencing as healthy controls. RESULTS: Upregulation of the T helper (Th) 2/Th22 pathway, Th17 antimicrobial genes, and natural T-regulatory cell abundance in the PBMCs of AD cases was observed, whereas TGF-ß signaling and NK-cell signaling were decreased. Dupilumab treatment reversed the increase in the expression of Th2 cytokine receptors. WGCNA identified two immune-related modules that were correlated significantly with the efficacy of dupilumab. Hub gene MAP2K3 and UBE2L3 of these two modules demonstrated potential predictive ability for efficacy in the RNA-sequencing group by Spearman correlation, ROC analysis, and regression analysis, which was further validated in additional 21 AD cases. CONCLUSION: We firstly revealed the molecular phenotype of PBMCs in Chinese patients with AD, and uncovered two molecules that might be useful for prediction of the efficacy of dupilumab.

Serum biomarker-based endotypes of atopic dermatitis in China and prediction for efficacy of dupilumab.

BACKGROUND: Atopic dermatitis (AD) is a highly heterogeneous disease clinically and biologically. Serum biomarkers have been utilized for endotype identification and have the potential to be predictors for treatment. OBJECTIVES: To explore the serum biomarker-based endotypes of Chinese patients with AD and to identify biomarkers for prediction of the efficacy of dupilumab. METHODS: Sera from 125 patients with moderate-to-severe AD and 60 normal controls (NC) were analysed for 24 cytokines/chemokines using the magnetic Luminex assay. After the patients received 16 weeks of dupilumab treatment, the efficacy was evaluated, and blood eosinophils, serum immunoglobulin (Ig) E and biomarkers were measured. RESULTS: Chinese patients with moderate-to-severe AD were characterized by T-helper (Th)2-dominant serum biomarkers that were mixed with differentially increased Th1-, Th17- and Th22-type cytokines/chemokines, and it was mainly Th2-type serum biomarkers that were positively correlated with disease severity and eosinophil counts. Adult (but not adolescent or elderly) patients with AD showed a consistent and more significant increase of biomarkers across different types of inflammation. The patients were grouped into two clusters by unsupervised k-means analysis, which were differentially associated with inflammation. Treatment with dupilumab decreased the levels of most cytokines/chemokines analysed. While there was no difference between the two clusters in the efficacy of dupilumab, baseline levels of CD25/soluble interleukin (sIL)-2Rα, IL-31 and IL-36ß were identified as predictive factors associated with the efficacy. CONCLUSIONS: Our study revealed two inflammation-related endotypes of Chinese patients with AD based on serum biomarkers. High levels of CD25/sIL-2Rα, IL-31 and IL-36ß might predict good efficacy of dupilumab treatment.

Dysregulated lipidome of sebum in patients with atopic dermatitis.

BACKGROUND: Lipids are the major components of skin barrier, mainly produced by keratinocytes and sebaceous glands. Previous studies on barrier dysfunction of atopic dermatitis (AD) mainly focus on the lipids from keratinocytes, whereas the role of sebaceous gland-derived lipids in AD has long been underrecognized. METHODS: The sebum secreted on the skin surface of AD patients was measured using the Delfin Sebum Scale. Sebum was collected using Sebutape patches and subjected for liquid chromatography tandem-mass spectrometry (LC-MS/MS) analysis. Multivariate data analysis was applied to explore the relationship among the lipidome, clinical features, and sebaceous gland-related molecules. RESULTS: The amount of sebum secreted from sebaceous glands was decreased in AD patients and was negatively correlated with the barrier function and disease severity. LC-MS/MS revealed the lipidome of sebum, which clustered distinctly between AD patients and healthy individuals. Among the differential lipid subclasses, triglycerides (TG) were exclusively decreased in AD patients and correlated with disease severity. The first principal component scores of AD patients, which represented the main signature of the lipidome, were positively correlated with the SCORAD scores and were significantly different across the patient groups with differential clinical symptoms such as skin dryness and pruritus. Further analysis on the previously published transcriptome data revealed aberrant expression of lipid metabolism-related genes in non-lesional skin of AD patients, which was associated with skin inflammation and barrier dysfunction and mainly derived from inner root sheath keratinocytes and sebaceous gland cells. CONCLUSION: Atopic dermatitis patients demonstrated a deviated lipidome of sebum and aberrant lipid metabolism in sebaceous glands, indicating a possible role of lipids from sebaceous glands in the pathogenesis of AD.

A dysregulated sebum-microbial metabolite-IL-33 axis initiates skin inflammation in atopic dermatitis.

Microbial dysbiosis in the skin has been implicated in the pathogenesis of atopic dermatitis (AD); however, whether and how changes in the skin microbiome initiate skin inflammation, or vice versa, remains poorly understood. Here, we report that the levels of sebum and its microbial metabolite, propionate, were lower on the skin surface of AD patients compared with those of healthy individuals. Topical propionate application attenuated skin inflammation in mice with MC903-induced AD-like dermatitis by inhibiting IL-33 production in keratinocytes, an effect that was mediated through inhibition of HDAC and regulation of the AhR signaling pathway. Mice lacking sebum spontaneously developed AD-like dermatitis, which was improved by topical propionate application. A proof-of-concept clinical study further demonstrated the beneficial therapeutic effects of topical propionate application in AD patients. In summary, we have uncovered that the dysregulated sebum-microbial metabolite-IL-33 axis might play an initiating role in AD-related skin inflammation, thereby highlighting novel therapeutic strategies for the treatment of AD.

Identification of Molecular Signatures in Mild Intrinsic Atopic Dermatitis by Bioinformatics Analysis.

BACKGROUND: Atopic dermatitis (AD) is recognized as a common inflammatory skin disease and frequently occurred in Asian and Black individuals. OBJECTIVE: Since the limitation of dataset associated with human severe AD, this study aimed to screen potential novel biomarkers involved in mild AD. METHODS: Expression profile data (GSE75890) were obtained from the database of Gene Expression Omnibus. Using limma package, the differentially expressed genes (DEGs) between samples from AD and healthy control were selected. Furthermore, function analysis was conducted. Meanwhile, the protein-protein interaction (PPI) network and transcription factor (TF)-miRNA-target regulatory network were constructed. And quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the expressions patterns of key genes. RESULTS: In total, 285 DEGs including 214 upregulated and 71 downregulated genes were identified between samples from two groups. The upregulated DEGs were mainly involved in nine pathways, such as hematopoietic cell lineage, pertussis, p53 signaling pathway, staphylococcus aureus infection, and cell cycle, while tight junction was the only pathway enriched by the downregulated DEGs. Cyclin B (CCNB)1, CCNB2, cyclin A (CCNA)2, C-X-C motif chemokine ligand (CXCL)10, and CXCL9 were key nodes in PPI network. The TF-miRNA-target gene regulatory network focused on miRNAs such as miR-106b, miR-106a, and miR-17, TFs such as nuclear factor kappa B subunit 1, RELA proto-oncogene, Sp1 transcription factor, and genes such as matrix metallopeptidase 9, peroxisome proliferator activated receptor gamma , and serpin family E member 1. Moreover, the upregulation of these genes, including CCNB1, CCNB2, CCNA2, CXCL10, and CXCL9 were confirmed by qRT-PCR. CONCLUSION: CCNB1, CCNB2, CCNA2, and CXCL9 might be novel markers of mild AD. miR-106b and miR-17 may involve in regulation of immune response in AD patients.

Sublingual immunotherapy of atopic dermatitis in mite-sensitized patients: a multi-centre, randomized, double-blind, placebo-controlled study.

Allergen-specific immunotherapy is widely used for allergic rhinitis and asthma treatment worldwide. This study explored the efficacy and safety of sublingual immunotherapy (SLIT) with the extracts of Dermatophagoides Farinae (D. farinae Drops) on house dust mites (HDM)-induced atopic dermatitis (AD). 239 patients with HDM-induced AD were recruited and exposure to a multi-centre, randomized, double-blind, and placebo-controlled clinical trials for 36 weeks, which were randomly divided into placebo and sublingual D. farinae Drops groups (high-dose, medium-dose and low-dose), respectively. Statistical analysis was performed in three groups: Full Analysis Set, Per Protocol Set and Safety Set. 48 cases have withdrawn from the study before the end of study. As primary outcomes, significant decreases in scoring atopic dermatitis and total medication score were showed in medium-dose and high-dose D. farinae Drops groups. In the sixth visit, the skin lesion area showed a statistically significant difference between high-dose/medium-dose D. farinae Drops group and placebo group (p < .05). Most adverse events are slight, and no life-threatening adverse drug reaction happened. Our research demonstrates the beneficial effect of SLIT with high or medium dose D. farinae Drops on AD, and the treatment was well tolerated.

IFN-γ-induced microRNA-29b up-regulation contributes tokeratinocyte apoptosis in atopic dermatitis through inhibiting Bcl2L2.

Recent evidence has suggested that microRNAs (miRNAs) may play a significant role in the pathogenesis of inflammatory skin conditions such as atopic dermatitis (AD). The aim of the present study was to evaluate the potential functions of miRNAs in AD and to identify the underlying mechanisms. We firstly analyzed miRNA expression in the skin lesions of patients with AD using microarray analysis. Validation analysis was performed in skin biopsy specimens and in serum using quantitative reverse transcription PCR (qRT-PCR). The relationship between microRNA-29b (miR-29b) and development of AD was further explored. Subsequently, gain- and loss-of-function studies were performed to determine the functions of miR-29b in interferon-γ (IFN-d)-induced keratinocytes (KCs) apoptosis. Further bioinformatics analysis and luciferase reporter assays were performed to predict its target genes, then the effects of miR-29b on the expression of BCL2-like2 (Bcl2L2) were investigated using qRT-PCR and western blot analysis. Finally, KCs were transfected with miR-29b mimics or Bcl2L2 siRNA (si-Bcl2L2) to explore the mechanism by which miR-29b plays in the pro-apoptotic roles in IFN-γ-treated keratinocytes. The miR-29b was found to be one of the most significantly up-regulated miRNAs in the skin lesions of patients with AD, as compared with healthy control and its expression was statistically associated with the development of AD. We, therefore, selected miR-29b as a candidate miRNA and investigated its function. Our in vitro data showed that the keratinocytes apoptosis induced by IFN-duced by IFN-ptosis induced by IFN-vestigated its function. Our stically associated with the deve particular, we identified Bcl2L2 as a direct target of miR-29b. More importantly, siRNA-induced knockdown of Bcl2L2 attenuated the protective effects of miR-29b inhibition on keratinocytes apoptosis. These results suggested that miR-29b knockdown may play an important role in preventing cell apoptosis in IFN-cktreated keratinocytes, and these effects might be partially through regulation of Bcl2L2. These findings revealed that the miR-29b/Bcl2L2 regulatory axis was involved in the pathogenesis of AD and suggested that knockdown of miR-29b might be a novel therapeutic target for AD.

Genomic variations of the mevalonate pathway in porokeratosis.

Porokeratosis (PK) is a heterogeneous group of keratinization disorders. No causal genes except MVK have been identified, even though the disease was linked to several genomic loci. Here, we performed massively parallel sequencing and exonic CNV screening of 12 isoprenoid genes in 134 index PK patients (61 familial and 73 sporadic) and identified causal mutations in three novel genes (PMVK, MVD, and FDPS) in addition to MVK in the mevalonate pathway. Allelic expression imbalance (AEI) assays were performed in 13 lesional tissues. At least one mutation in one of the four genes in the mevalonate pathway was found in 60 (98%) familial and 53 (73%) sporadic patients, which suggests that isoprenoid biosynthesis via the mevalonate pathway may play a role in the pathogenesis of PK. Significantly reduced expression of the wild allele was common in lesional tissues due to gene conversion or some other unknown mechanism. A G-to-A RNA editing was observed in one lesional tissue without AEI. In addition, we observed correlations between the mutations in the four mevalonate pathway genes and clinical manifestations in the PK patients, which might support a new and simplified classification of PK under the guidance of genetic testing.

Serum levels of thymus and activation-regulated chemokine can be used in the clinical evaluation of atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by the predominant infiltration of Th2-type cells in lesional skin. Thymus and activation-regulated chemokine (TARC) is overproduced in AD patients, and its serum levels are significantly higher in individuals with AD than in those with other inflammatory skin diseases. OBJECTIVES: The purpose of this study was to examine whether serum levels of TARC can assess the severity of AD and be used in the clinical evaluation of AD. METHODS: A total of 73 AD patients, 11 patients with generalized atopic eczema (AE), and 30 healthy control subjects were enrolled. SCORAD (SCORing of Atopic Dermatitis) indices were calculated according to skin symptom scores. The Th2 chemokines TARC kit was then used to obtain serum TARC values in each group. Finally, statistical analysis was used to identify any correlations between serum TARC level and SCORAD index in AD and AE patients. RESULTS: Mean serum TARC values were 159.95 in healthy controls, 146.46 in the mild AD group, 202.71 in the moderate AD group, 1216.61 in the severe AD group and 1554.50 in the severe AE group. The serum TARC level was significantly correlated with SCORAD score in AD patients (P < 0.01). However, there was no significant correlation between SCORAD score and TARC in AE patients (P = 0.610). CONCLUSIONS: The serum TARC level can be used to assess the severity of AD and as a reference index for the fast clinical evaluation of AD.

Clinical analysis and etiology of porokeratosis.

The present study was performed in order to define the clinical manifestations of porokeratosis, with particular emphasis on genital porokeratosis. A total of 55 cases of porokeratosis were retrospectively reviewed between 2000 and 2007 from Huashan Hospital (Shanghai, China). Out of 55 cases, there were 22 cases of porokeratosis of Mibelli, 17 cases of disseminated superficial actinic porokeratosis (DSAP), 15 cases of disseminated superficial porokeratosis and one case of linear porokeratosis. The ratio of males to females was 39:16. Among them, 12 cases had a family history of porokeratosis. During the five-year follow-up period, no malignant transformation was observed and no further aggravation of lesions was detected. The results indicated that the initial region of DSAP in the Chinese population may differ from Caucasians. In combination with other studies, the present study found that genital porokeratosis in the Chinese population is often associated with pruritus. Since no recurrence was observed in cases treated with surgical excision, it was suggested that surgical excision is a viable treatment strategy and should be used for porokeratotic lesions if possible. In addition, regular follow-ups are required, since the aggravation of porokeratosis may cause the development of malignancy transformation.

Gene expression profiling of porokeratosis.

BACKGROUND: Porokeratosis (PK) represents a heterogeneous group of disorders of keratinization and has a wide variety of clinical manifestations. PK may exhibit similarities with psoriasis at both clinical and molecular levels. The genetic basis and pathogenesis for PK remain elusive. METHODS: We studied the transcriptional profiles of three pairwise lesional and uninvolved skin biopsies from patients with different subtypes of PK using the Illumina BeadArray platform. RESULTS: A total of 37 upregulated genes were identified in our study, including wound-induced keratins, S100 calcium-binding protein genes involved in epidermal differentiation, as well as genes involved in mediating intercellular communication and the immune response. To our knowledge, this is the first study that characterizes the immune profile of PK lesions. CONCLUSIONS: Here, we report that keratinocytes (KCs)-harboring lesions have activated and overexpressed wound-induced keratin genes, which appear to be coregulated with other genes involved in mediating epidermal differentiation, intercellular communication and immunity. This study, from the perspective of gene profiling, supports that gene misregulation in PK mimics that of psoriasis. Our data indicate that the genes implicated in the T-cell-mediated immune response pathway and activation of KCs play a key role in the pathogenesis of PK.

Two closely linked variations in actin cytoskeleton pathway in a Chinese pedigree with disseminated superficial actinic porokeratosis.

BACKGROUND: Disseminated superficial actinic porokeratosis (DSAP) is an uncommon autosomal dominant chronic keratinization disorder, characterized by multiple superficial keratotic lesions surrounded by a slightly raised keratotic border. Recently, SSH1 was identified as the DSAP candidate gene. OBJECTIVE: Our purpose was to determine the locus of DSAP and identify the candidate gene(s) of the disease. METHODS: Genome-wide scanning and linkage analysis were performed in a 6-generation Chinese family with DSAP. The coding exons and promoter region of the candidate genes were screened for the nucleotide variations. RESULTS: A missense mutation (p.Ser63Asn) in SSH1 and a variation (dbSNP3759383: G>A) in the promoter region of ARPC3 were closely linked with DSAP in the pedigree. CONCLUSION: Both SSH1 and ARPC3 are involved in the actin cytoskeleton pathway and interacted with adherent junctions in the epidermal cells. We suggested that cytoskeleton disorganization in epidermal cells was likely associated with the pathogenesis of DSAP.