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.

CREB1-driven CXCR4hi neutrophils promote skin inflammation in mouse models and human patients.

Neutrophils have a pathogenic function in inflammation via releasing pro-inflammatory mediators or neutrophil extracellular traps (NETs). However, their heterogeneity and pro-inflammatory mechanisms remain unclear. Here, we demonstrate that CXCR4hi neutrophils accumulate in the blood and inflamed skin in human psoriasis, and correlate with disease severity. Compared to CXCR4lo neutrophils, CXCR4hi neutrophils have enhanced NETs formation, phagocytic function, neutrophil degranulation, and overexpression of pro-inflammatory cytokines and chemokines in vitro. This is accompanied by a metabolic shift in CXCR4hi neutrophils toward glycolysis and lactate release, thereby promoting vascular permeability and remodeling. CXCR4 expression in neutrophils is dependent on CREB1, a transcription factor activated by TNF and CXCL12, and regulated by de novo synthesis. In vivo, CXCR4hi neutrophil infiltration amplifies skin inflammation, whereas blockade of CXCR4hi neutrophils through CXCR4 or CXCL12 inhibition leads to suppression of immune responses. In this work, our study identifies CREB1 as a critical regulator of CXCR4hi neutrophil development and characterizes the contribution of CXCR4hi neutrophils to vascular remodeling and inflammatory responses in skin.

Association of psoriasis with depression, anxiety, and suicidality: A bidirectional two-sample Mendelian randomization study.

Psoriasis is a chronic, refractory inflammatory skin disease, with a high prevalence of psychiatric comorbidities, including depression, anxiety, and even suicidality, which may in turn initiate or exacerbate skin inflammation. However, the causal relationships between these comorbidities remain unclear. To investigate the cause-effect relationships between psoriasis and mental disorders including depression, anxiety, and suicidality, we conducted a bidirectional two-sample Mendelian randomization (MR) study utilizing summary statistics from the most comprehensive genome-wide association studies of psoriasis (n = 306 123), broad depression (n = 500 199), major depressive disorder (n = 173 005), anxiety (n = 17 310), and suicide attempts (n = 50 264). Using the random-effects inverse-variance weighted method as primary method, the forward MR analyses indicated that psoriasis was significantly associated with higher odds of broad depression (odds ratio [OR] 1.030, 95% confidence interval [CI] 1.010-1.051, P = 0.003) and suggestively associated with an increased risk of major depressive disorder (OR 1.054, 95% CI 1.002-1.109, P = 0.040), but not with the risk of anxiety (P = 0.160) or suicide attempts (P = 0.648). In reverse MR analyses, significant causal impact of broad depression (OR 1.363, 95% CI 1.103-1.684, P = 0.004) and major depressive disorder (OR 1.890, 95% CI 1.285-2.781, P = 0.001), but not anxiety (P = 0.787) and suicide attempts (P = 0.961) on psoriasis risk was observed. In addition, the results of primary analysis are consistent across sensitivity analyses, albeit the MR-Egger regression model produced wide CIs and negative results in several analyses. In conclusion, this MR study indicates a bidirectional causal relationship between psoriasis and depression that was previously unrecognized, which highlights the significance of screening for depression in psoriasis patients and initiating appropriate interventions. Further studies are required to elucidate the pathophysiology of the bidirectional causal relationship between these two conditions.

CXCL12/CXCR4 Axis Drives the Chemotaxis and Differentiation of B Cells in Bullous Pemphigoid.

Bullous pemphigoid (BP) is an autoimmune bullous skin disease characterized by autoantibodies against the hemidesmosomal proteins in the skin and mucous membranes. The efficiency of B-cell‒targeting biologics in BP indicates the important role of B cells in its pathogenesis. However, abnormal B-cell migration and differentiation in BP require further elucidation. We showed that the number of antibody-secreting cells increased in the circulation and skin lesions of patients with BP and was correlated with disease severity. Bulk RNA sequencing of the peripheral B cells identified 171 upregulated and 408 downregulated genes in patients with BP compared with those in healthy controls, among which CXCR4 was significantly upregulated. Notably, CXCR4+ B cells were enriched in BP skin lesions and exhibited antibody-secreting cell characteristics. Correspondingly, an elevated level of CXCL12, the CXCR4 ligand, was detected in the blister fluid and serum of patients with BP, mediating the chemotaxis and accumulation of CXCR4+ B cells to BP skin lesions. Moreover, CXCL12 activated the transcription factor c-Myc, thus promoting B-cell differentiation into antibody-secreting cells and facilitating autoantibody production, which was blocked by CXCR4 inhibitor in vitro. Collectively, our study reveals that the CXCL12/CXCR4 axis plays a pathogenic role in modulating B-cell trafficking and differentiation, thus targeting CXCR4 represents a potential strategy for treating BP and other autoimmune diseases.

EZH2-dependent epigenetic modulation of histone H3 lysine-27 contributes to psoriasis by promoting keratinocyte proliferation.

Psoriasis is characterized by keratinocyte hyperproliferation. While significant progress has been made in understanding the molecular mechanism regulating the proliferation of keratinocytes, little is known about the epigenetic factors that control this process. EZH2 and EZH2 mediated trimethylation of histone H3 lysine 27 (H3K27me3) was previously shown ectopically expressed in carcinoma and mediated proliferation, thereby we sought to clarify the role of EZH2-H3K27me3 in the proliferation of psoriatic keratinocyte. Interestingly, we found that EZH2 and H3K27me3 were both overexpressed in the epidermis of psoriatic lesional skin compared to normal skin. In vitro, the expression of EZH2 and H3K27me3 was stimulated in human keratinocytes treated with mixture of psoriasis-related cytokines pool (TNF-α, IFN-γ, IL-17A, and IL-22). Knockdown of EZH2 significantly reduced keratinocyte proliferative activity. Results from mRNA microarray analysis suggested that Kallikrein-8 (KLK8) might be the target gene of EZH2 in psoriatic keratinocytes. Overexpression or knockdown KLK8 could partially reverse the abnormal proliferation of keratinocytes caused by knockdown or overexpression of EZH2. In vivo, the inhibitor of EZH2, GSK126 could ameliorate the imiquimod-induced psoriasiform lesion. These results suggest that EZH2 might be a therapeutic target for the treatment of psoriasis.

Comparative effectiveness of different therapies for treating striae distensae: A systematic review and network meta-analysis.

BACKGROUND: Striae distensae (SD) are common and aesthetically undesirable dermal lesions. The aim of this study is to comprehensively evaluate the effectiveness of different therapies in treating striae distensae using network meta-analysis. METHODS: A systematic search of electronic databases up to December 1, 2019 was conducted. Randomized controlled trails (RCTs) examining the effectiveness of different methods in treating striae distensae were included. The primary outcomes are clinical effective rate and patient's satisfaction degree. Risk of bias was assessed by the Cochrane risk of bias tool. Network meta-analysis was based on Bayesian framework. RESULTS: Fourteen trails that met the criteria with 651 subjects were included. The results of the network meta-analysis show that topical tretinoin combined bipolar radiofrequency showed the highest probability of being the best method to improve the clinical effectiveness and patient satisfaction rate of treating SD (84.5% and 95.7% respectively), closely followed by bipolar radiofrequency (75.3% and 84.3% respectively). Among laser treatment, CO2 fractional laser is superior to other lasers in the clinical effectiveness and patient satisfaction (72.0% and 58.1% respectively). Statistics showed the topical tretinoin was the worst-performing option in improving the clinical effectiveness and patient satisfaction rate of SD treatment (5.4% and 5.1% respectively). CONCLUSION: Based on the results of network meta-analysis, we recommend treating striae distensae with bipolar radio frequency combined topical tretinoin. The commonly used CO2 fractional laser can be considered as alternative treatment candidate. Additional large-scale RCTs are necessary to obtain more precise estimates of their relative efficacy.

Neutrophil Extracellular Traps Promote Inflammatory Responses in Psoriasis via Activating Epidermal TLR4/IL-36R Crosstalk.

Epidermal infiltration of neutrophils is a hallmark of psoriasis, where their activation leads to release of neutrophil extracellular traps (NETs). The contribution of NETs to psoriasis pathogenesis has been unclear, but here we demonstrate that NETs drive inflammatory responses in skin through activation of epidermal TLR4/IL-36R crosstalk. This activation is dependent upon NETs formation and integrity, as targeting NETs with DNase I or CI-amidine in vivo improves disease in the imiquimod (IMQ)-induced psoriasis-like mouse model, decreasing IL-17A, lipocalin2 (LCN2), and IL-36G expression. Proinflammatory activity of NETs, and LCN2 induction, is dependent upon activation of TLR4/IL-36R crosstalk and MyD88/nuclear factor-kappa B (NF-κB) down-stream signaling, but independent of TLR7 or TLR9. Notably, both TLR4 inhibition and LCN2 neutralization alleviate psoriasis-like inflammation and NETs formation in both the IMQ model and K14-VEGF transgenic mice. In summary, these results outline the mechanisms for the proinflammatory activity of NETs in skin and identify NETs/TLR4 as novel therapeutic targets in psoriasis.

Mechanical Stretch Exacerbates Psoriasis by Stimulating Keratinocyte Proliferation and Cytokine Production.

Psoriasis is a chronic inflammatory autoimmune skin disease that often occurs in rubbed areas undergoing a strong mechanical stretch, such as the elbows and knees. However, the pathologic role of mechanical tension in psoriasis remains unclear. In this study, we investigated the contribution of keratinocyte mechanical stretch to the clinical features of psoriasis. We found that keratinocyte proliferation and skin barrier-associated gene expression increased significantly after 24 hours of continuous stretching. Additionally, continuous stretching induced the production of psoriasis-associated proinflammatory cytokines, antibacterial peptides, and chemokines in primary human keratinocytes. Furthermore, we established a murine model of skin expansion by implanting a dilator into the dorsum of BALB/c mice to assess the effect of mechanical stretch on the epidermis in vivo. The dilator-implanted mice displayed prominent epidermal hyperproliferation, impaired skin barrier function, and up-regulation of psoriasis-associated cytokines in epidermal keratinocytes. Most importantly, the dilator-implanted psoriatic mice treated with imiquimod or IL-23 displayed an aggravated psoriatic phenotype compared with mice without dilator implantation. Collectively, our results suggest that mechanical stretch can exacerbate psoriatic lesions by promoting cell proliferation and amplifying the production of proinflammatory cytokines by keratinocytes. Thus, our findings provide new insights into the pathogenesis of psoriasis.

Decreased expression levels of complement regulator CD55 contribute to the development of bullous pemphigoid.

Bullous pemphigoid is a common autoimmune blistering disease of the elderly associated with autoantibody-mediated complement activation, and complement dysregulation is critical for its pathogenesis. As a crucial regulator of the complement system, CD55 has been widely studied in autoimmune diseases. Here, we investigated the involvement of CD55 in bullous pemphigoid, as little is known regarding its role in this disease. We found that CD55 levels were significantly lower in the lesions of patients with bullous pemphigoid (n = 8) compared to those in skin samples from healthy controls (n = 6). Interestingly, CD55 depletion in HaCaT human keratinocytes enhanced autoantibody-mediated complement activation. Moreover, complement activation was blocked by exogenous recombinant CD55 protein in both skin sections and keratinocytes exposed to pathogenic antibodies from patients with bullous pemphigoid. Notably, a significant increase in the expression of TNF-α and IFN-γ, administration of which downregulated CD55 levels in HaCaT cells, was observed in the sera of patients with bullous pemphigoid (n = 38) compared to that in healthy controls (n = 19). We found that ERK1/2 is involved in both TNF-α- and IFN-γ-induced CD55 downregulation. Thus, CD55 deficiency is a crucial factor in bullous pemphigoid pathogenesis, suggesting that increasing CD55 levels may exert a therapeutic effect.

Identification of Immunodominant Th2-Cell Epitopes in Chinese Patients with Bullous Pemphigoid.

Bullous pemphigoid (BP) is a subepidermal autoimmune blistering disease caused by autoantibodies targeting the juxtamembranous extracellular noncollagenous 16A (NC16A) domain of human collagen XVII (also known as BP180). Because T-helper (Th) cells are essential for antibody responses to antigens, we adopted an assay to map the immunodominant Th2-cell epitopes in NC16A. We synthesized 22 overlapping peptides spanning the entire sequence of BP180-NC16A and investigated the reactivity of Th2 cells from patients with BP to these peptides using the Enzyme-Linked ImmunoSpot (ELISPOT) assay. We screened two epitope peptides, P2 (492-506 aa: VRKLKARVDELERIR) and P5 (501-515 aa: ELERIRRSILPYGDS), and confirmed that these epitopes play a dominant role in stimulating CD4+ T-cell proliferation and Th2 IL-4 cytokine production, and activating B cells to secrete autoantibodies. These immunodominant epitopes are HLA-DR-restricted and were observed in subjects with different HLA alleles. This work contributes to elucidation of the epitope-mediated immunologic pathogenesis of BP, and the identified Th2-cell epitopes are candidates for epitope-specific therapeutic strategy.

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.

Semaphorin 4D from CD15+ Granulocytes via ADAM10-Induced Cleavage Contributes to Antibody Production in Bullous Pemphigoid.

Autoreactive B-cell activation and antibody production are critical events for the development of bullous pemphigoid (BP). However, the mechanism that is involved in the modulation of B-cell activation and autoantibody generation has not been fully understood. Semaphorin 4D (Sema4D, or CD100) plays important roles in immune regulation related to B cells, but its implications in BP remain obscure. The aim of our study was to characterize Sema4D and the underlying mechanism contributing to the autoimmune features of BP. We found that soluble Sema4D (sSema4D) levels were elevated and correlated with disease severity and activity in serum and blister fluids from patients with BP. Additionally, Sema4D-expressing cells accumulated in subepidermal blisters of BP lesions. In patient-derived peripheral blood mononuclear cells, by promoting the differentiation of B cells into plasmablasts, sSema4D boosted anti-BP180/anti-BP230 antibody production in a time- and dose-dependent manner, which may be attributed to CD72-mediated activation of Akt/NF-κB phosphorylated (p-)65/ERK cascades in B cells. We determined that a disintegrin and metalloproteinase 10 is a proteolytic enzyme for the cleavage of sSema4D from CD15+ granulocytes instead of T cells, which is probably responsible for the high concentration of sSema4D in BP blister fluid and serum. These findings suggest that Sema4D is a crucial participant in BP pathogenesis.

Association of HLA class I and class II alleles with bullous pemphigoid in Chinese Hans.

BACKGROUND: Bullous pemphigoid (BP) is one of the most common autoimmune skin diseases. Associations of genes, especially human leukocyte antigen (HLA)-DQ alleles, with BP indicate that genetic predisposition contributes to the disease. OBJECTIVES: To evaluate the association of HLA class I and HLA class II alleles with susceptibility to BP in the northern Chinese Han population. METHODS: We performed genotype for HLA-A, -B, -C, -G, -DPA1, -DPB1, -DQA1, -DQB1 and -DRB1 loci in 105 patients with BP by Sanger sequence-based typing (SBT) method. These data were compared with a local control cohort of 420 age- and sex-matched cases. RESULTS: Among the HLA alleles described herein, the susceptibility alleles associated with a high prevalence of BP were A*11:01 (OR = 1.9 Pc = 0.017); B*37:01 (OR = 8, Pc = 1.811 × 10-6); G*01:01 (OR = 3.61, Pc = 2.839 × 10-15) and G*01:06 (OR = 2.22, Pc = 0.025); DQA1*01:05 (OR = 4.87, Pc = 5.822 × 10-5), DQA1*05:05 (OR = 2.64, Pc = 9.114 × 10-4), and DQA1*05:08 (OR = 10.2, Pc = 0.016); DQB1*03:01 (OR = 1.69, Pc = 0.048) and DQB1*05:01 (OR = 3.42, Pc = 7.28 × 10-6); and DRB1*10:01 (OR = 6.85, Pc = 2.63 × 10-6). To the contrary, HLA-DQA1*01:02 (OR = 0.46, Pc = 8.603 × 10-4) and DQA1*01:03 (OR = 0.38, Pc = 0.048); DQB1*02:02 (OR = 0.28, Pc = 0.016); and DRB1*07:01 (OR = 0.26, Pc = 0.004) had significant associations with protection against BP. In addition, the frequency of haplotype HLA-DRB1*13-DQA1*05-DQB1*03 (OR = 12.32, Pc = 0.026) in BP patients was significantly higher than those in controls. CONCLUSION: Our data demonstrated that the alleles and haplotypes found in this study may be important differential genetic markers for susceptibility to or protection against BP in individuals of northern Chinese Han population.

Semaphorin4D Drives CD8+ T-Cell Lesional Trafficking in Oral Lichen Planus via CXCL9/CXCL10 Upregulations in Oral Keratinocytes.

Chemokine-mediated CD8+ T-cell recruitment is an essential but not well-established event for the persistence of oral lichen planus (OLP). Semaphorin 4D (Sema4D)/CD100 is implicated in immune dysfunction, chemokine modulation, and cell migration, which are critical aspects for OLP progression, but its implication in OLP pathogenesis has not been determined. In this study, we sought to explicate the effect of Sema4D on human oral keratinocytes and its capacity to drive CD8+ T-cell lesional trafficking via chemokine modulation. We found that upregulations of sSema4D in OLP tissues and blood were positively correlated with disease severity and activity. In vitro observation revealed that Sema4D induced C-X-C motif chemokine ligand 9/C-X-C motif chemokine ligand 10 production by binding to plexin-B1 via protein kinase B-NF-κB cascade in human oral keratinocytes, which elicited OLP CD8+ T-cell migration. We also confirmed using clinical samples that elevated C-X-C motif chemokine ligand 9/C-X-C motif chemokine ligand 10 levels were positively correlated with sSema4D levels in OLP lesions and serum. Notably, we determined matrix metalloproteinase-9 as a new proteolytic enzyme for the cleavage of sSema4D from the T-cell surface, which may contribute to the high levels of sSema4D in OLP lesions and serum. Our findings conclusively revealed an amplification feedback loop involving T cells, chemokines, and Sema4D-dependent signal that promotes OLP progression.