Fibroblasts in immune-mediated inflammatory diseases: The soil of inflammation.

As one of the most abundant stromal cells, fibroblasts are primarily responsible for the production and remodeling of the extracellular matrix. Traditionally, fibroblasts have been viewed as quiescent cells. However, recent advances in multi-omics technologies have demonstrated that fibroblasts exhibit remarkable functional diversity at the single-cell level. Additionally, fibroblasts are heterogeneous in their origins, tissue locations, and transitions with stromal cells. The dynamic nature of fibroblasts is further underscored by the fact that disease stages can impact their heterogeneity and behavior, particularly in immune-mediated inflammatory diseases such as psoriasis, inflammatory bowel diseases, and rheumatoid arthritis, etc. Fibroblasts can actively contribute to the disease initiation, progression, and relapse by responding to local microenvironmental signals, secreting downstream inflammatory factors, and interacting with immune cells during the pathological process. Here we focus on the development, plasticity, and heterogeneity of fibroblasts in inflammation, emphasizing the need for a developmental and dynamic perspective on fibroblasts.

Clinical characteristics and heterogeneity of generalized pustular psoriasis: A comparative study in a large retrospective cohort.

Generalized pustular psoriasis (GPP) is a rare and potentially life-threatening skin disease and the clinical heterogeneity of which is largely unknown. Retrospective cohort analysis was conducted on hospitalized GPP patients between January 2010 and November 2022. A total of 416 patients with GPP and psoriasis vulgaris (PV) respectively were included, matched 1:1 by sex and age. The heterogeneity of GPP was stratified by PV history and age. Compared with PV, GPP was significantly associated with prolonged hospitalization (11.7 vs. 10.3 day, p < 0.001), elevated neutrophil lymphocyte ratio (NLR) (5.93 vs. 2.44, p < 0.001) and anemia (13.9% vs. 1.2%, p < 0.001). Moreover, GPP alone (without PV history) was a relatively severer subtype with higher temperature (37.6°C vs. 38.0°C, p = 0.002) and skin infections (5.2% vs. 11.4%, p = 0.019) than GPP with PV. For patients across different age, compared with juvenile patients, clinical features support a severer phenotype in middle-aged, including higher incidence of anaemia (7.5% vs. 16.0%, p = 0.023) and NLR score (3.83 vs. 6.88, p < 0.001). Interleukin-6 (r = 0.59), high density lipoprotein cholesterol (r = -0.56), albumin (r = -0.53) and C-reactive protein-to-albumin ratio (r = 0.49) were the most relevant markers of severity in GPP alone, GPP with PV, juvenile and middle-aged GPP, respectively. This retrospective cohort suggests that GPP is highly heterogeneous and GPP alone and middle-aged GPP exhibit severe disease phenotypes. More attention on the heterogeneity of this severe disease is warranted to meet the unmet needs and promote the individualized management of GPP.

Biological agent exerts therapeutic effects by reversing abnormalities in amino acid metabolic pathways in psoriasis.

Psoriasis is a common chronic inflammatory skin disease with a complex pathogenesis involving immune system dysregulation and inflammation. Previous studies have indicated that metabolic abnormalities are closely related to the development and occurrence of psoriasis. However, the specific involvement of amino acid metabolism in the pathogenesis of psoriasis remains unclear. In this study, we conducted a comprehensive analysis of amino acid metabolism pathway changes in psoriasis patients using transcriptome data, genome-wide association studies (GWASs) data, and single-cell data. Our findings revealed 11 significant alterations in amino acid metabolism pathways within psoriatic lesions, with notable restorative changes observed after biological therapy. Branched-chain amino acids, tyrosine and arginine metabolism have a causal relationship with the occurrence of psoriasis and may play a crucial role by promoting the proliferation and differentiation of the keratinocytes or immune-related pathways. Activation of phenylalanine, tyrosine and tryptophan biosynthesis suggests a favourable prognosis of psoriasis after treatment. Additionally, we identified the abnormal metabolic pathways in specific cell types and key gene sets that contribute to amino acid metabolic disorders in psoriasis. Overall, our study enhances understanding of the role of metabolism in the pathogenesis of psoriasis and provides potential targets for developing new therapeutic strategies for the disease.

Assessment of relationships between bullous pemphigoid and neurological diseases: A bidirectional two-sample Mendelian randomization study.

Bullous pemphigoid (BP) is the most prevalent autoimmune vesiculobullous skin illness that tends to affect the elderly. Growing evidence has hinted a correlation between BP and neurological diseases. However, existing observational studies contained inconsistent results, and the causality and direction of their relationship remain poorly understood. To assess the causal relationship between BP and neurological disorders, including Alzheimer's disease (AD), multiple sclerosis (MS), Parkinson's disease (PD), and stroke. A bidirectional two-sample Mendelian randomization (MR) adopted independent top genetic variants as instruments from the largest accessible genome-wide association studies (GWASs), with BP (n = 218 348), PD (n = 482 730), AD (n = 63 926), stroke (n = 446 696), and MS (n = 115 803). Inverse variance weighted (IVW), MR-Egger, weighted mode methods, weighted median, and simple mode were performed to explore the causal association. Multiple sensitivity analyses, MR-Pleiotropy Residual Sum and Outlier (PRESSO) was used to evaluate horizontal pleiotropy and remove outliers. With close-to-zero effect estimates, no causal impact of BP on the risk of the four neurological diseases was discovered. However, we found that MS was positively correlated with higher odds of BP (OR = 1.220, 95% CI: 1.058-1.408, p = 0.006), while no causal associations were observed between PD (OR = 0.821, 95% CI: 0.616-1.093, p = 0.176), AD (OR = 1.066, 95% CI: 0.873-1.358, p = 0.603), stroke (OR = 0.911, 95% CI: 0.485-1.713, p = 0.773) and odds of BP. In summary, no causal impact of BP on the risk of PD, AD, MS and stroke was detected in our MR analysis. However, reverse MR analysis identified that only MS was positively correlated with higher odds of BP, but not PD, AD and stroke.

A critical role of the endothelial S-phase kinase-associated protein 2/phosphatase and tensin homologue axis in angiogenesis and psoriasis.

BACKGROUND: Psoriasis is a common chronic skin disorder. Pathologically, it features abnormal epidermal proliferation, infiltrating inflammatory cells and increased angiogenesis in the dermis. Aberrant expression of E3 ubiquitin ligase and a dysregulated protein ubiquitination system are implicated in the pathogenesis of psoriasis. OBJECTIVES: To examine the potential role of S-phase kinase-associated protein 2 (Skp2), an E3 ligase and oncogene, in psoriasis. METHODS: Gene expression and protein levels were evaluated with quantitative reverse transcriptase polymerase chain reaction, Western blotting, immunohistochemistry and immunofluorescence staining of skin samples from patients with psoriasis vulgaris and an imiquimod (IMQ)-induced mouse model, as well as from cultured endothelial cells (ECs). Protein interaction, substrate ubiquitination and degradation were examined using co-immunoprecipitation, Western blotting and a cycloheximide chase assay in human umbilical vein ECs. Angiogenesis was measured in vitro using human dermal microvascular ECs (HDMECs) for BrdU incorporation, migration and tube formation. In vivo angiogenesis assays included chick embryonic chorioallantoic membrane, the Matrigel plug assay and quantification of vasculature in the mouse lesions. Skp2 gene global knockout (KO) mice and endothelial-specific conditional KO mice were used. RESULTS: Skp2 was increased in skin samples from patients with psoriasis and IMQ-induced mouse lesions. Immunofluorescent double staining indicated a close association of Skp2 expression with excessive vascularity in the lesional dermal papillae. In HDMECs, Skp2 overexpression was enhanced, whereas Skp2 knockdown inhibited EC proliferation, migration and tube-like structure formation. Mechanistically, phosphatase and tensin homologue (PTEN), which suppresses the phosphoinositide 3-kinase/Akt pathway, was identified to be a novel substrate for Skp2-mediated ubiquitination. A selective inhibitor of Skp2 (C1) or Skp2 small interfering RNA significantly reduced vascular endothelial growth factor-triggered PTEN ubiquitination and degradation. In addition, Skp2-mediated ubiquitination depended on the phosphorylation of PTEN by glycogen synthase kinase 3ß. In the mouse model, Skp2 gene deficiency alleviated IMQ-induced psoriasis. Importantly, tamoxifen-induced endothelial-specific Skp2 KO mice developed significantly ameliorated psoriasis with diminished angiogenesis of papillae. Furthermore, topical use of the Skp2 inhibitor C1 effectively prevented the experimental psoriasis. CONCLUSIONS: The Skp2/PTEN axis may play an important role in psoriasis-associated angiogenesis. Thus, targeting Skp2-driven angiogenesis may be a potential approach to treating psoriasis.

Formylpeptide receptor 1 contributes to epidermal barrier dysfunction-induced skin inflammation through NOD-like receptor C4-dependent keratinocyte activation.

BACKGROUND: Skin barrier dysfunction may both initiate and aggravate skin inflammation. However, the mechanisms involved in the inflammation process remain largely unknown. OBJECTIVES: We sought to determine how skin barrier dysfunction enhances skin inflammation and molecular mechanisms. METHODS: Skin barrier defect mice were established by tape stripping or topical use of acetone on wildtype mice, or filaggrin deficiency. RNA-Seq was employed to analyse the differentially expressed genes in mice with skin barrier defects. Primary human keratinocytes were transfected with formylpeptide receptor (FPR)1 or protein kinase R-like endoplasmic reticulum (ER) kinase (PERK) small interfering RNA to examine the effects of these gene targets. The expressions of inflammasome NOD-like receptor (NLR)C4, epidermal barrier genes and inflammatory mediators were evaluated. RESULTS: Mechanical (tape stripping), chemical (acetone) or genetic (filaggrin deficiency) barrier disruption in mice amplified the expression of proinflammatory genes, with transcriptomic profiling revealing overexpression of formylpeptide receptor (Fpr1) in the epidermis. Treatment with the FPR1 agonist fMLP in keratinocytes upregulated the expression of the NLRC4 inflammasome and increased interleukin-1ß secretion through modulation of ER stress via the PERK-eIF2α-C/EBP homologous protein pathway. The activation of the FPR1-NLRC4 axis was also observed in skin specimens from old healthy individuals with skin barrier defect or elderly mice. Conversely, topical administration with a FPR1 antagonist, or Nlrc4 silencing, led to the normalization of barrier dysfunction and alleviation of inflammatory skin responses in vivo. CONCLUSIONS: In summary, our findings show that the FPR1-NLRC4 inflammasome axis is activated upon skin barrier disruption and may explain exaggerated inflammatory responses that are observed in disease states characterized by epidermal dysfunction. Pharmacological inhibition of FPR1 or NLRC4 represents a potential therapeutic target.

Serine deficiency exacerbates psoriatic skin inflammation by regulating S-adenosyl methionine-dependent DNA methylation and NF-κB signalling activation in keratinocytes.

BACKGROUND: Serine metabolism is crucial for tumour oncogenesis and immune responses. S-adenosyl methionine (SAM), a methyl donor, is typically derived from serine-driven one-carbon metabolism. However, the involvement of serine metabolism in psoriatic skin inflammation remains unclear. OBJECTIVES: To investigate the association between serine metabolism and psoriatic skin inflammation. METHODS: Clinical samples were collected from patients with psoriasis and the expression of serine biosynthesis enzymes was evaluated. The HaCaT human keratinocyte cell line was transfected with small interfering RNA (siRNA) of key enzyme or treated with inhibitors. RNA sequencing and DNA methylation assays were performed to elucidate the mechanisms underlying serine metabolism-regulated psoriatic keratinocyte inflammation. An imiquimod (IMQ)-induced psoriasis mouse model was established to determine the effect of the SAM administration on psoriatic skin inflammation. RESULTS: The expression of serine synthesis pathway enzymes, including the first rate-limiting enzyme in serine biosynthesis, phosphoglycerate dehydrogenase (PHGDH), was downregulated in the epidermal lesions of patients with psoriasis compared with that in healthy controls. Suppressing PHGDH in keratinocytes promoted the production of proinflammatory cytokines and enrichment of psoriatic-related signalling pathways, including the tumour necrosis factor-alpha (TNF-α) signalling pathway, interleukin (IL)-17 signalling pathway and NF-κB signalling pathway. In particular, PHGDH inhibition markedly promoted the secretion of IL-6 in keratinocytes with or without IL-17A, IL-22, IL-1α, oncostatin M and TNF-α (mix) stimulation. Mechanistically, PHGDH inhibition upregulated the expression of IL-6 by inhibiting SAM-dependent DNA methylation at the promoter and increasing the binding of myocyte enhancer factor 2A. Furthermore, PHGDH inhibition increased the secretion of IL-6 by increasing the activation of NF-κB via SAM inhibition. SAM treatment effectively alleviated IMQ-induced psoriasis-like skin inflammation in mice. CONCLUSIONS: Our study revealed the crucial role of PHGDH in antagonising psoriatic skin inflammation and indicated that targeting serine metabolism may represent a novel therapeutic strategy for treating psoriasis.

Cross-disease characterization of fibroblast heterogeneities and their pathogenic roles in skin inflammation.

Fibroblasts are critical pro-inflammatory regulators in chronic inflammatory and fibrotic skin diseases. However, fibroblast heterogeneity and the absence of a unified cross-disease taxonomy have hindered our understanding of the shared/distinct pathways in non-communicable skin inflammation. By integrating 10× single-cell data from 75 skin samples, we constructed a single-cell atlas across inflammatory and fibrotic skin diseases and identified 9 distinct subsets of skin fibroblasts. We found a shared subset of CCL19+ fibroblasts across these diseases, potentially attracting and educating immune cells. Moreover, COL6A5+ fibroblasts were a distinct subset implicated in the initiation and relapse of psoriasis, which tended to differentiate into CXCL1+ fibroblasts, inducing neutrophil chemotaxis and infiltration; while CXCL1+ fibroblasts exhibited a more heterogeneous response to certain inflammatory conditions. Differentiation trajectory and regulatory factors of these fibroblast subsets were also revealed. Therefore, our study presents a comprehensive atlas of skin fibroblasts and highlights pathogenic fibroblast subsets in skin disorders.

Neutrophil extracellular traps promote keratinocyte inflammation via AIM2 inflammasome and AIM2-XIAP in psoriasis.

The infiltration of neutrophils in the epidermis and the release of neutrophil extracellular traps (NETs) are important events in the pathogenesis of psoriasis, but the regulatory roles and internal mechanism of NETs in psoriasis are largely unknown. Here, we demonstrate that NETs can activate the absent-in-melanoma-2 (AIM2) inflammasome in keratinocytes through the p38-MAPK signalling pathway, and targeting NETs with CI-amidine in vivo reduces AIM2 expression and ameliorates imiquimod-induced psoriasis-like phenotype in mice. Notably, NETs-activated AIM2 in keratinocytes not only promotes IL-1ß production through the classical inflammasome pathway but also promotes IFN-γ production via X-linked inhibitor of apoptosis protein (XIAP), thereby mediating the immune responses of keratinocytes. In conclusion, our study demonstrates that the NETs-AIM2 axis exerts multiple pro-inflammatory effects on keratinocytes and may serve as a potential target for psoriasis therapy.

Activation of the C3a anaphylatoxin receptor inhibits keratinocyte proliferation by regulating keratin 6, keratin 16, and keratin 17 in psoriasis.

Emerging evidence suggests that signaling through the C3a anaphylatoxin receptor (C3aR) protects against various inflammation-related diseases. However, the role of C3aR in psoriasis remains unknown. The purpose of this study was to investigate the possible protective role of C3aR in psoriasis and to explore the underlying molecular mechanisms. We initially found that the psoriatic epidermis exhibited significantly decreased C3aR expression. C3aR showed protective roles in mouse models of imiquimod (IMQ)- and interleukin-23-induced psoriasis. Furthermore, increased epidermal thickness and keratin 6 (K6), K16, and K17 expression occurred in the ears and backs of C3aR-/- mice. Pharmacological treatment with a C3aR agonist ameliorated IMQ-induced psoriasiform lesions in mice and decreased the expression of K6, K16, and K17. Additionally, the signal transducer and activator of transcription 3 (STAT3) pathway participated in the protective function of C3aR. More importantly, the expression levels of K6, K16, and K17 in keratinocytes were all restored in HaCaT cells transfected with a C3aR-overexpression plasmid after treating them with colivelin (a STAT3 activator). Our findings demonstrate that C3aR protects against the development of psoriasis and suggest that C3aR confers protection by negatively regulating K6, K16, and K17 expression in a STAT3-dependent manner, thus inhibiting keratinocyte proliferation and helping reverse the pathogenesis of psoriasis.

Fractional carbon dioxide vaginal laser treatment of stress urinary incontinence: Remodeling of vaginal tissues and improving pelvic floor structures.

OBJECTIVE: To demonstrate remodeling of vaginal biomechanical and physiological properties using vaginal fractional carbon dioxide (CO2 ) laser treatment of stress urinary incontinence (SUI). MATERIALS AND METHODS: The study cohort included 26 patients with SUI between October 2019 and November 2020. Patients were treated with two sessions of FemTouch vaginal fractional CO2 laser with a one-month interval. Three subjective assessments were administered to all patients: female sexual function index (FSFI), vaginal health index score (VHIS), and international consultation on incontinence questionnaire-short form (ICIQ-SF). Vaginal tissue biopsies were taken from 6 patients before treatment and one-month after the final treatment. Vaginal tactile imaging (VTI) measurements, ultrasonography, and magnetic resonance imaging (MRI) scans were performed before treatment and 10-12-months after treatment in 10, 9, and 6 patients, respectively. RESULTS: The average age of the cohort was 39.5 ± 12.0 years. The overall scores for FSFI, VHIS, and ICIQ-SF significantly improved in patients after each treatment sessions as compared with baseline scores. VTI showed significantly increased pressure resistance of both the anterior and posterior vaginal walls after treatment. Ultrasonography showed significant decreases in bladder neck mobility and urethrovesical angle during the Valsalva maneuver after treatment. MRI scans showed significant decreases in the length of the vaginal anterior wall after treatment. Histological examination confirmed that the laser treatment led to a thicker stratified squamous epithelium layer as compared to the baseline. CONCLUSIONS: Our results demonstrated that vaginal fractional CO2 laser treatment can restore vaginal biomechanical and physiological properties by increasing vaginal tightening and improving pelvic floor structures.

Enhanced phenotype of calcipotriol-induced atopic dermatitis in filaggrin-deficient mice.

Impaired function of filaggrin (FLG) is a major predisposing factor for atopic dermatitis (AD). Several studies on FLG-deficient (Flg-/- ) mice have indicated an essential role for FLG in the skin barrier and the development of AD, but none of the studies have described the characteristics on Flg-/- mice with calcipotriol (CPT)-induced atopic dermatitis, which restricts the comprehensive understanding of functions of FLG. The present study sought to generate Flg-/- mice and applied CPT to produce AD-like dermatitis for in vivo analysis of the FLG functions. CPT was applied on the skin of Flg-/- mice to establish the AD-like dermatitis mouse model. The lesion inflammation was evaluated by gross ear thickness, histopathology, immunofluorescence, and cytokine production. Also, mucopolysaccharide polysulfate (MPS) and ceramide were used to observe the therapeutic function in this model. The results showed that the inflammation of CPT-induced dermatitis in Flg-/- mice was more severer than that of wild-type (WT) mice, as evident by the increased level of gross appearance, ear thickness, inflammatory cell infiltration (mast cells and CD3+ T cells), and inflammatory cytokine expression (interleukin (IL)-4, IL-6, IL-13, and thymic stromal lymphopoietin (TSLP)). The emollients MPS and ceramide partially restored the epidermal function and alleviated the skin inflammation in Flg-/- mice with CPT-induced AD-like dermatitis. The current study demonstrated that skin barrier protein FLG is critical in the pathogenesis of AD. Also, the AD mouse model induced by CPT in Flg-/- mice could be utilized to search for drug targets in AD.

Neutrophil extracellular traps contribute to immune dysregulation in bullous pemphigoid via inducing B-cell differentiation and antibody production.

Bullous pemphigoid (BP), an autoimmune skin disease, is characterized by autoantibodies against hemidesmosomal proteins in the skin and mucous membranes. Neutrophils infiltrate BP skin lesions, however, their role in immune dysregulation remains unclear. We investigated whether BP involves aberrant neutrophil extracellular traps (NETs) formation in skin lesions and circulation; and examined the triggers and deleterious immuno-inflammatory consequences. In the present study, we found that circulating NET-related biomarker levels increased in serum and blister fluid of BP patients and significantly correlated with disease severity. Additionally, circulating neutrophils from BP patients displayed enhanced spontaneous NETs formation than healthy controls. In vitro, BP180-NC16A immune complexes-induced NETosis in neutrophils from BP patients, which was abrogated by Fcγ receptor and/or NADPH pathway blockade. Furthermore, the elevated levels of NETs from BP patients boosted autoantibody production by inducing B-cell differentiation into plasma cells, mediated by MAPK P38 cascade activation. Together, our findings provide strong evidence that NETs are involved in a pathogenic loop, causing excessive differentiation of B cells and promotion of autoantibody production. Hence, targeting aberrant neutrophil responses will provide novel potential targets for the treatment of BP.

Mutations in 3ß-hydroxysteroid-δ8, δ7-isomerase paradoxically benefit epidermal permeability barrier homeostasis in mice.

Inherited or acquired blockade of distal steps in the cholesterol synthetic pathway results in ichthyosis, due to reduced cholesterol production and/or the accumulation of toxic metabolic precursors, while inhibition of epidermal cholesterol synthesis compromises epidermal permeability barrier homeostasis. We showed here that 3ß-hydroxysteroid-δ8, δ7-isomerase-deficient mice (TD), an analog for CHILD syndrome in humans, exhibited not only lower basal transepidermal water loss rates, but also accelerated permeability barrier recovery despite the lower expression levels of mRNA for epidermal differentiation marker-related proteins and lipid synthetic enzymes. Moreover, TD mice displayed low skin surface pH, paralleled by increased expression levels of mRNA for sodium/hydrogen exchanger 1 (NHE1) and increased antimicrobial peptide expression, compared with wild-type (WT) mice, which may compensate for the decreased differentiation and lipid synthesis. Additionally, in comparison with WT controls, TD mice showed a significant reduction in ear thickness following challenges with either phorbol ester or oxazolone. However, TD mice exhibited growth retardation. Together, these results demonstrate that 3ß-hydroxysteroid-δ8, δ7-isomerase deficiency does not compromise epidermal permeability barrier in mice, suggesting that alterations in epidermal function depend on which step of the cholesterol synthetic pathway is interrupted. But whether these findings in mice could be mirrored in humans remains to be determined.

Multi-omics study in monozygotic twins confirm the contribution of de novo mutation to psoriasis.

BACKGROUND: Genome-wide association studies have identified over 120 risk loci for psoriasis. However, most of the variations are located in non-coding region with high frequency and small effect size. Pathogenetic variants are rarely reported except HLA-C*0602 with the odds ratio being approximately 4.0 in Chinese population. Although rare variations still account for a small proportion of phenotypic variances in complex diseases, their effect on phenotypes is large. Recently, more and more studies focus on the low-frequency functional variants and have achieved a certain amount of success. METHOD: Whole genome sequencing and sanger sequencing was performed on 8 MZ twin pairs discordant for psoriasis to scan and verified the de novo mutations (DNMs). Additionally, 665 individuals with about 20 years' medical history versus 2054 healthy controls and two published large population studies which had about 8 years' medical history (including 10,727 cases versus 10,582 controls) were applied to validate the enrichment of rare damaging mutations in two DNMs genes. Besides, to verify the pathogenicity of candidate DNM in C3, RNA-sequencing for CD4+, CD8+ T cells of twins and lesion, non-lesion skin of psoriasis patients were carried out. Meanwhile, the enzyme-linked immunosorbent assay kit was used to detect the level of C3, C3b in the supernatant of peripheral blood. RESULT: A total of 27 DNMs between co-twins were identified. We found six of eight twins carry HLA-C∗0602 allele which have large effects on psoriasis. And it is interesting that a missense mutation in SPRED1 and a splice region mutation in C3 are found in the psoriasis individuals in the other two MZ twin pairs without carrying HLA-C*0602 allele. In the replication stage, we found 2 loss-of-function (LOF) variants of C3 only in 665 cases with about 20 years' medical history and gene-wise analysis in 665 cases and 2054 controls showed that the rare missense mutations in C3 were enriched in cases (OR = 1.91, P = 0.0028). We further scanned the LOF mutations of C3 in two published studies (about 8 years' medical history), and found one LOF mutation in the case without carrying HLA-C*0602. In the individual with DNM in C3, RNA sequencing showed the expression level of C3 in skin was significant higher than healthy samples in public database (TPM fold change = 1.40, P = 0.000181) and ELISA showed protein C3 in peripheral blood was higher (~2.2-fold difference) than the other samples of twins without DNM in C3. CONCLUSION: To the best of our knowledge, this is the first report that DNM in C3 is the likely pathological mutations, and it provided a better understanding of the genetic etiology of psoriasis and additional treatments for this disease.

Inducible nitric oxide synthase is required for epidermal permeability barrier homeostasis in mice.

Nitric oxide (NO) regulates a variety of epidermal functions, including epidermal proliferation, differentiation and cutaneous wound healing. However, whether nitric oxide (NO) and its synthetic enzymes regulate epidermal permeability barrier homeostasis is not clear. In the present study, we employed inducible nitric oxide synthase (iNOS) KO mice to explore the role of iNOS in epidermal permeability barrier homeostasis. Our results showed that iNOS mice displayed a comparable levels of basal transepidermal water loss rates, stratum corneum hydration and skin surface pH to their wild-type mice, but epidermal permeability barrier recovery was significantly delayed both 2 and 4 hours after acute barrier disruption by tape stripping. In parallel, expression levels of mRNA for epidermal differentiation-related proteins and lipid synthetic enzymes were lower in iNOS KO mice versus wild-type controls. Topical applications of two structurally unrelated NO donors to iNOS KO mice improved permeability barrier recovery kinetics and upregulated expression levels of mRNA for epidermal differentiation-related proteins and lipid synthetic enzymes. Together, these results indicate that iNOS and its product regulate epidermal permeability barrier homeostasis in mice.

Neutrophil exosomes enhance the skin autoinflammation in generalized pustular psoriasis via activating keratinocytes.

Generalized pustular psoriasis (GPP) is a rare and severe inflammatory skin disease that can be life-threatening. Gene mutations are found in some cases, but its immune pathogenesis is largely unknown. Here, we observed that the neutrophil:lymphocyte ratio in patients with GPP was higher than that in healthy controls and decreased after effective treatment. Neutrophils isolated from patients with GPP induced higher expressions of inflammatory genes including IL-1ß, IL-36G, IL-18, TNF-α, and C-X-C motif chemokine ligands in keratinocytes than normal neutrophils did. Moreover, neutrophils from patients with GPP secreted more exosomes than controls, which were then rapidly internalized by keratinocytes, increasing the expression of these inflammatory molecules via activating NF-κB and MAPK signaling pathways. The proteomic profiles in neutrophil exosomes further characterized functional proteins and identified olfactomedin 4 as the critical differentially expressed protein that mediates the autoimmune inflammatory responses of GPP. These results demonstrate that neutrophil exosomes have an immune-regulatory effect on keratinocytes, which modulates immune cell migration and autoinflammation in GPP.-Shao, S., Fang, H., Zhang, J., Jiang, M., Xue, K., Ma, J., Zhang, J., Lei, J., Zhang, Y., Li, B., Yuan, X., Dang, E., Wang, G. Neutrophil exosomes enhance the skin autoinflammation in generalized pustular psoriasis via activating keratinocytes.

The Phytopathogenic Fungus Pallidocercospora crystallina-Caused Localized Subcutaneous Phaeohyphomycosis in a Patient with a Homozygous Missense CARD9 Mutation.

PURPOSE: In the past decade, an increasing number of otherwise healthy individuals suffered from invasive fungal infections due to inherited CARD9 mutations. Herein, we present a patient with a homozygous CARD9 mutation who was suffering from localized subcutaneous phaeohyphomycosis caused by the phytopathogenic fungus Pallidocercospora crystallina which has not been reported to cause infections in humans. METHODS: The medical history of our patient was collected. P. crystallina was isolated from the biopsied tissue. To characterize this novel pathogen, the morphology was analyzed, whole-genome sequencing was performed, and the in vivo immune response was explored in mice. Whole-exome sequencing was carried out with samples from the patient's family. Finally, the expression and function of mutated CARD9 were investigated. RESULTS: A dark red plaque was on the patient's left cheek for 16 years and was diagnosed as phaeohyphomycosis due to a P. crystallina infection. Whole-genome sequencing suggested that that this strain had a lower pathogenicity. The in vivo immune response in immunocompetent or immunocompromised mice indicated that P. crystallina could be eradicated within a few weeks. Whole-exome sequencing revealed ahomozygous missense mutation in CARD9 (c.1118G>C p.R373P). The mRNA and protein expression levels were similar among cells carrying homozygous (C/C), heterozygous (G/C), and wild-type (G/G) CARD9 alleles. Compared to PBMCs or neutrophils with heterozygous or wild-type CARD9 alleles, however, PBMCs or neutrophils with homozygous CARD9 alleles showed impaired anti-P. crystallina effects. CONCLUSION: Localized subcutaneous phaeohyphomycosis caused by P. crystallina was reported in a patient with a homozygous CARD9 mutation. Physicians should be aware of the possibility of a CARD9 mutation in seemingly healthy patients with unexplainable phaeohyphomycosis.

Mesenchymal stem cells in psoriatic lesions affect the skin microenvironment through circular RNA.

Psoriasis is an autoimmune skin disease. Our previous studies revealed abnormal immune regulation of skin mesenchymal stem cells (S-MSCs) in psoriatic lesions. Circular RNA (circRNA) molecules were recently discovered as a new class of non-coding regulatory RNAs. Their role in the pathogenesis of psoriasis has not yet been studied. To explore potential circRNA-mediated mechanisms of S-MSCs in the pathogenesis of psoriasis, we sequenced mRNAs and circRNAs of MSCs from normal skin and psoriatic lesions, followed by functional prediction and interaction analyses. In total, 129 circRNAs were differentially expressed, including 123 up-regulated and 6 down-regulated circRNAs, in MSCs from psoriatic lesions. Pathway analysis showed that the genes significantly down-regulated in psoriatic as compared to normal S-MSCs were mainly involved in JAK-STAT signalling. According to a circRNA-miRNA-mRNA interaction network, the expression of circRNAs associated with these mRNAs was also down-regulated in MSCs of psoriatic skin lesions. Knockdown of the circRNA gene chr2:206992521|206994966 reduced the capacity of S-MSCs to inhibit T-cell proliferation upon co-culture in normal as well as lesion-derived S-MSCs. Secreted-cytokine profiles (IL-6, IL-11 and hepatocyte growth factor) were also similar in normal and lesion-derived S-MSCs after circRNA knockdown. Thus, the circRNA chr2:206992521|206994966 in S-MSCs from psoriatic lesions affects the activity of T lymphocytes in local lesions by influencing their cytokine secretion. Taken together, our findings indicate that circRNA mediates the role of S-MSCs in the pathogenesis of psoriasis.

Proinflammatory role of blister fluid-derived exosomes in bullous pemphigoid.

Bullous pemphigoid is an autoimmune inflammatory disorder characterized by the presence of autoantibodies against bullous pemphigoid autoantigens, leading to dermal-epidermal separation with consequent blister formation. However, whether and how the components of blister fluid exacerbate the progression of bullous pemphigoid is unclear. Exosomes are nanometre-sized vesicles released from cells into the body fluid, where they can transmit signals throughout the body. In the present study, we isolated and characterized exosomes from blister fluids of patients with bullous pemphigoid, evaluated their proinflammatory role, and identified the underlying molecular mechanisms. We found that exosomes isolated from blister fluids of patients with bullous pemphigoid showed the expected size and expressed the marker proteins CD63, CD81, and CD9. Additionally, blister fluid-derived exosomes were internalized by human primary keratinocytes, inducing the production of critical inflammatory cytokines and chemokines. Western blotting analysis showed robust and rapid activation of the extracellular signal-regulated kinase 1/2 and signal transducer and activator of transcription 3 signalling pathways in human primary keratinocytes after stimulation with blister fluid-derived exosomes. We also found that blister fluid-derived exosomes indirectly induced neutrophil trafficking by upregulating C-X-C motif chemokine ligand 8 in vitro. Furthermore, CD63 was localized mostly to keratinocytes and infiltrative granulocytes in skin lesions, suggesting that these cells were the possible sources of exosomes in blister fluid. Using mass spectrometry, we analysed the proteomes of blister fluid-derived exosomes and identified a variety of proteins implicated in inflammatory and immune responses. Together, our findings provide strong evidence that blister fluid-derived exosomes are involved in the local autoinflammatory responses of the skin associated with bullous pemphigoid. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.