SERPINB3/B4 is Increased in Psoriasis and Rosacea Lesions and has Pro-inflammatory Effects in Mouse Models of these Diseases.

Psoriasis and rosacea are both chronic inflammatory skin disorders resulted from aberrant keratinocyte-immune cell crosstalk, but the common molecular foundations for these two conditions are poorly understood. Here, we reveal that both psoriasis and rosacea patients, as well as their mice models, have significantly elevated expressions of SERPINB3/B4 (members of serine protease inhibitor) in the lesional skin. Skin inflammation in mice that resembles both psoriasis and rosacea is prevented by SERPINB3/B4 deficiency. Mechanistically, we demonstrate that SERPINB3/B4 positively induces NF-κB signaling activation, thereby stimulating disease-characteristic inflammatory chemokines and cytokines production in keratinocytes, and promoting the chemotaxis of CD4+ T cells. Our results suggest that, in keratinocytes, SERPINB3/B4 may be involved in the pathogenesis of both psoriasis and rosacea by stimulating NF-κB signaling, and they indicate a possible treatment overlap between these two diseases.

Targeting Aquaporin-3 Attenuates Skin Inflammation in Rosacea.

Rosacea is a common inflammatory skin disorder mediated by the dysregulation of both keratinocytes and T cells. Here, we report that aquaporin 3 (AQP3), a channel protein that mediates the transport of water/glycerol, was highly expressed in the epidermis and CD4+ T cells of both rosacea patients and experimental mice. Specifically, AQP3 deletion blocked the development of rosacea-like skin inflammation in model mice with LL37-induced rosacea-like disease. We also present mechanistic evidence showing that AQP3 was essential to the activation of NF-κB signaling and subsequent production of disease-characteristic chemokines in keratinocytes. Moreover, we show that AQP3 was upregulated during T cell differentiation and promotes helper T (Th) 17 differentiation possibly via the activation of STAT3 signaling. Our findings reveal that AQP3-mediated activation of NF-κB in keratinocytes and activation of STAT3 in CD4+ T cells acted synergistically and contributed to the inflammation in rosacea.

TLR7 promotes skin inflammation via activating NFκB-mTORC1 axis in rosacea.

Rosacea is a chronic inflammatory skin disease originated from damaged skin barrier and innate/adaptive immune dysregulation. Toll-like receptors (TLRs) sense injured skin and initiate downstream inflammatory and immune responses, whose role in rosacea is not fully understood. Here, via RNA-sequencing analysis, we found that the TLR signaling pathway is the top-ranked signaling pathway enriched in rosacea skin lesions, in which TLR7 is highlighted and positively correlated with the inflammation severity of disease. In LL37-induced rosacea-like mouse models, silencing TLR7 prevented the development of rosacea-like skin inflammation. Specifically, we demonstrated that overexpressing TLR7 in keratinocytes stimulates rapamycin-sensitive mTOR complex 1 (mTORC1) pathway via NFκB signaling. Ultimately, TLR7/NFκ B/mTORC1 axis promotes the production of cytokines and chemokines, leading to the migration of CD4+T cells, which are infiltrated in the lesional skin of rosacea. Our report reveals the crucial role of TLR7 in rosacea pathogenesis and indicatesa promising candidate for rosacea treatments.

Whole genome sequencing identifies genetic variants associated with neurogenic inflammation in rosacea.

Rosacea is a chronic inflammatory skin disorder with high incidence rate. Although genetic predisposition to rosacea is suggested by existing evidence, the genetic basis remains largely unknown. Here we present the integrated results of whole genome sequencing (WGS) in 3 large rosacea families and whole exome sequencing (WES) in 49 additional validation families. We identify single rare deleterious variants of LRRC4, SH3PXD2A and SLC26A8 in large families, respectively. The relevance of SH3PXD2A, SLC26A8 and LRR family genes in rosacea predisposition is underscored by presence of additional variants in independent families. Gene ontology analysis suggests that these genes encode proteins taking part in neural synaptic processes and cell adhesion. In vitro functional analysis shows that mutations in LRRC4, SH3PXD2A and SLC26A8 induce the production of vasoactive neuropeptides in human neural cells. In a mouse model recapitulating a recurrent Lrrc4 mutation from human patients, we find rosacea-like skin inflammation, underpinned by excessive vasoactive intestinal peptide (VIP) release by peripheral neurons. These findings strongly support familial inheritance and neurogenic inflammation in rosacea development and provide mechanistic insight into the etiopathogenesis of the condition.

Signalling by senescent melanocytes hyperactivates hair growth.

Niche signals maintain stem cells in a prolonged quiescence or transiently activate them for proper regeneration1. Altering balanced niche signalling can lead to regenerative disorders. Melanocytic skin nevi in human often display excessive hair growth, suggesting hair stem cell hyperactivity. Here, using genetic mouse models of nevi2,3, we show that dermal clusters of senescent melanocytes drive epithelial hair stem cells to exit quiescence and change their transcriptome and composition, potently enhancing hair renewal. Nevus melanocytes activate a distinct secretome, enriched for signalling factors. Osteopontin, the leading nevus signalling factor, is both necessary and sufficient to induce hair growth. Injection of osteopontin or its genetic overexpression is sufficient to induce robust hair growth in mice, whereas germline and conditional deletions of either osteopontin or CD44, its cognate receptor on epithelial hair cells, rescue enhanced hair growth induced by dermal nevus melanocytes. Osteopontin is overexpressed in human hairy nevi, and it stimulates new growth of human hair follicles. Although broad accumulation of senescent cells, such as upon ageing or genotoxic stress, is detrimental for the regenerative capacity of tissue4, we show that signalling by senescent cell clusters can potently enhance the activity of adjacent intact stem cells and stimulate tissue renewal. This finding identifies senescent cells and their secretome as an attractive therapeutic target in regenerative disorders.

Efficacy and safety of antibiotic agents in the treatment of rosacea: a systemic network meta-analysis.

Background: Antibiotics are considered the backbone of rosacea management, especially for controlling inflammatory papules and pustules. We aim to evaluate the efficacy and safety of varied prescriptions and doses of antibiotics in treating rosacea by network meta-analysis. Methods: In this study, we compared all available randomized controlled trials (RCTs) that have studied systemic and topical antibiotics and placebo in rosacea therapy. We searched databases such as the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, PubMed, Web of Science, and LILACS for published and unpublished RCTs on ClinicalTrials.gov before April 2023. The primary outcome was the improvement of the Investigator's Global Assessment (IGA) scores, and the secondary outcomes consisted of the improvement of the Patient's Global Assessment (PaGA) scores, Clinician's Erythema Assessment (CEA) scores, and adverse events (AEs). We used Bayesian random effects models for multiple treatment comparisons. Results: We identified 1,703 results through these databases. Thirty-one randomized trials with 8,226 patients were included. The heterogeneity and inconsistency between the trials were low, with a low risk of bias of all trials. Oral doxycycline 40 mg, minocycline 100 mg, and minocycline 40 mg, as well as topical ivermectin and metronidazole 0.75%, were effective in treating papules and pustules, thereby decreasing IGA in rosacea. Among these, minocycline 100 mg ranked top in efficacy. As for improving the PaGA scores, topical ivermectin, metronidazole 1%, and systemic oxytetracycline were effective, of which oxytetracycline worked the best. Both doxycycline 40 mg and metronidazole 0.75% presented no therapeutic effect for erythema. Considering the safety of the agents, systemic application of azithromycin and doxycycline 100 mg significantly increase the risk of AEs. Conclusion: Our review suggests that a high dosage of systemic minocycline is the most effective in treating rosacea phenotypes with papules and pustules with a low risk of AEs. However, there were no sufficient evidence-based data in exploring the influence of antibiotics on erythema. The phenotype of rosacea should be taken into consideration along with benefit and safety when making prescriptions due to AEs. Clinical Trial Registration: NCT(2016): http://cochranelibrary-wiley.com/o/cochrane/clcentral/articles/962/CN-01506962/frame.html NCT(2017): http://cochranelibrary-wiley.com/o/cochrane/clcentral/articles/764/CN-01565764/frame.html.

EGCG identified as an autophagy inducer for rosacea therapy.

Background: Rosacea is a common facial skin inflammatory disease featured by hyperactivation of mTORC1 signaling in the epidermis. Due to unclear pathogenesis, the effective treatment options for rosacea remain limited. Methods: Weighted gene co-expression network analysis (WGCNA) analyzed the relationship between epidermis autophagy and mTOR pathways in rosacea, and further demonstrated it through immunofluorescence and qPCR analysis. A potential therapeutic agent for rosacea was predicted based on the key genes of the WGCNA module. In vivo and in vitro experiments were conducted to verify its therapeutic role. Drug-target prediction (TargetNet, Swiss, and Tcmsp) and molecular docking offered potential pharmacological targets. Results: WGCNA showed that epidermis autophagy was related to the activation of mTOR pathways in rosacea. Next, autophagy was downregulated in the epidermis of rosacea, which was regulated by mTOR. In addition, the in vivo experiment demonstrated that autophagy induction could be an effective treatment strategy for rosacea. Subsequently, based on the key genes of the WGCNA module, epigallocatechin-3-gallate (EGCG) was predicted as a potential therapeutic agent for rosacea. Furthermore, the therapeutic role of EGCG on rosacea was confirmed in vivo and in vitro. Finally, drug-target prediction and molecular docking revealed that AKT1/MAPK1/MMP9 could be the pharmacological targets of EGCG in rosacea. Conclusion: Collectively, our findings revealed the vital role of autophagy in rosacea and identified that EGCG, as a therapeutic agent for rosacea, attenuated rosacea-like inflammation via inducing autophagy in keratinocytes.

Aberrant amino acid metabolism promotes neurovascular reactivity in rosacea.

Rosacea is a chronic skin disorder characterized by abnormal neurovascular and inflammatory conditions on the central face. Despite increasing evidence suggesting that rosacea is associated with metabolic disorders, the role of metabolism in rosacea pathogenesis remains unknown. Here, via a targeted metabolomics approach, we characterized significantly altered metabolic signatures in patients with rosacea, especially for amino acid-related metabolic pathways. Among these, glutamic acid and aspartic acid were highlighted and positively correlated with the disease severity in patients with rosacea. We further demonstrated that glutamic acid and aspartic acid can facilitate the development of erythema and telangiectasia, typical features of rosacea, in the skin of mice. Mechanistically, glutamic acid and aspartic acid stimulated the production of vasodilation-related neuropeptides from peripheral neurons and keratinocytes and induced the release of nitric oxide from endothelial cells and keratinocytes. Interestingly, we provided evidence showing that doxycycline can improve the symptoms of patients with rosacea possibly by targeting the amino acid metabolic pathway. These findings reveal that abnormal amino acid metabolism promotes neurovascular reactivity in rosacea and raise the possibility of targeting dysregulated metabolism as a promising strategy for clinical treatment.

Lithocholic acid promotes rosacea-like skin inflammation via G protein-coupled bile acid receptor 1.

BACKGROUND: Rosacea is a chronic inflammatory skin disorder with unclear etiology. Evidence showed that immunoinflammatory dysregulation was involved in the pathogenesis. Bile acids, as important participants of hepatoenteric circulation, play a vital role in immunoinflammatory regulation through peripheral blood circulation. However, whether it has effects on rosacea remains unknown. METHODS: Here, we performed a bile acid analysis on the serum samples of rosacea patients and healthy controls. Then we gavage G protein-coupled bile acid receptor 1 (TGR5) knockout mice with lithocholic acid (LCA) based on a LL37-induced rosacea-like model. We further overexpress TGR5 in HaCaT keratinocytes to figure out the downstream pathway. RESULTS: We found varied bile acid profile in the peripheral blood circulation of patients, especially the most significant increase in LCA. LCA promoted skin inflammation in LL37-induced rosacea-like mouse model. Our in vivo and in vitro results further demonstrated that LCA induced inflammatory cytokines and chemokines, thus exacerbated rosacea-like skin inflammation, via TGR5 in keratinocytes and LL37-induced rosacea-like mouse model. CONCLUSIONS: Therefore, we conclude that LCA promotes skin inflammation of rosacea via TGR5, and LCA-TGR5 axis may be a novel therapeutic target for rosacea.

Nav1.8 in keratinocytes contributes to ROS-mediated inflammation in inflammatory skin diseases.

Reactive oxygen species (ROS)-activated proinflammatory signals in keratinocytes play a crucial role in the immunoregulation of inflammatory skin diseases, including rosacea and psoriasis. Nav1.8 is a voltage-gated sodium ion channel, and its abnormal expression in the epidermal layer contributes to pain hypersensitivity in the skin. However, whether and how epidermal Nav1.8 is involved in skin immunoregulation remains unclear. This study was performed to identify the therapeutic role of Nav1.8 in inflammatory skin disorders. We found that Nav1.8 expression was significantly upregulated in the epidermis of rosacea and psoriasis skin lesions. Nav1.8 knockdown ameliorated skin inflammation in LL37-and imiquimod-induced inflammation mouse models. Transcriptome sequencing results indicated that Nav1.8 regulated the expression of pro-inflammatory mediators (IL1ß and IL6) in keratinocytes, thereby contributing to immune infiltration in inflammatory skin disorders. In vitro, tumor necrosis factor alpha (TNFα), a cytokine that drives the development of various inflammatory skin disorders, increased Nav1.8 expression in keratinocytes. Knockdown of Nav1.8 eliminated excess ROS production, thereby attenuating the TNFα-induced production of inflammatory mediators; however, a Nav1.8 blocker did not have the same effect. Mechanistically, Nav1.8 reduced superoxide dismutase 2 (SOD2) activity by directly binding to SOD2 to prevent its deacetylation and mitochondrial localization, subsequently inducing ROS accumulation. Collectively, our study describes a central role for Nav1.8 in regulating pro-inflammatory responses in the skin and indicates a novel therapeutic strategy for rosacea and psoriasis.

Neuroimmune Interaction: A Widespread Mutual Regulation and the Weapons for Barrier Organs.

Since the embryo, the nervous system and immune system have been interacting to regulate each other's development and working together to resist harmful stimuli. However, oversensitive neural response and uncontrolled immune attack are major causes of various diseases, especially in barrier organs, while neural-immune interaction makes it worse. As the first defense line, the barrier organs give a guarantee to maintain homeostasis in external environment. And the dense nerve innervation and abundant immune cell population in barrier organs facilitate the neuroimmune interaction, which is the physiological basis of multiple neuroimmune-related diseases. Neuroimmune-related diseases often have complex mechanisms and require a combination of drugs, posing challenges in finding etiology and treatment. Therefore, it is of great significance to illustrate the specific mechanism and exact way of neuro-immune interaction. In this review, we first described the mutual regulation of the two principal systems and then focused on neuro-immune interaction in the barrier organs, including intestinal tract, lungs and skin, to clarify the mechanisms and provide ideas for clinical etiology exploration and treatment.

Mediation roles of neutrophils and high-density lipoprotein (HDL) on the relationship between HLA-DQB1 and rosacea.

BACKGROUND: Though the previous genome-wide association studies found the association between HLA alleles and rosacea in the European populations, the data is lacking among the Asians. Moreover, neutrophils are important in the immune-related mechanism of rosacea, and dyslipidemia is closely related to rosacea. We aimed to explore the association between HLA genes and rosacea in Chinese rosacea patients, as well as the mediation effect of neutrophils, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) on the relationship between HLA genes and rosacea. METHODS: A total of 249 rosacea and 150 controls were ranked by the international investigator global rosacea severity scores. HLA genes, neutrophils, HDL, and LDL were detected. And their mediation effects on the relationship between HLA and rosacea risk or severity were analysed. RESULTS: HLA-DQB1*03:03 allele (OR = 41.89, 95% CI: 9.80 ∼ 179.09, p = 4.7*10-7), HLA-DQB1*04:02 allele (OR = 0.16, 95% CI: 0.03 ∼ 0.81, p = 0.026) and HLA-DQB1*03:03/05:02 genotype (OR = 5.57, 95% CI: 1.13 ∼ 27.52, p = 0.0351) were significantly associated with rosacea. Moreover, HLA-DQB1*03:03 allele (b = 1.434, SE = 0.217, p = 2.0*10-10), HLA-DQB1*05:01 allele (b = 0.894, SE = 0.33520, p = 0.008) and HLA-DQB1*03:03/06:01 genotype (b = 0.998, SE = 0.472, p = 0.040) were positively associated with rosacea severity. Furthermore, we found both neutrophils and HDL, instead of LDL, have mediation effects on the relationship between HLA-DQB1*03:03 and risk or severity of rosacea. CONCLUSIONS: We discovered novel susceptible HLA alleles for rosacea in the Chinese population, and disclosed the mediation effect of neutrophils and HDL on the relationship between HLA-DQB1 and rosacea, implying a possible correlation between rosacea and inflammatory or metabolic factors, providing hints for future studies in the mechanism of rosacea. Key messagesHLA-DQB1*03:03 allele, HLA-DQB1*04:02 allele and HLA-DQB1*03:03/05:02 genotype were significantly associated with rosacea.HLA-DQB1*03:03 allele, HLA-DQB1*05:01 allele and HLA-DQB1*03:03/06:01 genotype were positively associated with rosacea severity.Neutrophils and HDL have mediation effects on the relationship between HLA-DQB1*03:03 and risk or severity of rosacea.

Aging-Conferred SIRT7 Decline Inhibits Rosacea-Like Skin Inflammation by Modulating Toll-Like Receptor 2‒NF-κB Signaling.

Rosacea is a chronic inflammatory skin disorder that manifests abnormal enhanced sensitivity to environmental stimuli. The decreased prevalence of rosacea in aged population has been reported, but the underlying mechanism is unclear. In this study, we confirm that the rosacea-like skin inflammation induced by cathelicidin LL37 is alleviated in aged mice and mice with progeria. Primary mouse keratinocytes isolated from aged mice and human dermal fibroblasts that undergo senescence present a much lower sensitivity to proinflammatory stimuli. Mechanistically, toll-like receptor 2 (TLR2) is downregulated in the skin of both aged population and mice. Knockdown of TLR2 in young human dermal fibroblasts mimics the attenuated immune response to LL37 and TNF-α evidenced in aged human dermal fibroblasts, whereas overexpression of TLR2 in aged human dermal fibroblasts rescued this attenuation. At the molecular level, in response to inflammatory stimuli, SIRT7 mediates the upregulation of TLR2, which promotes the activation of NF-κB signaling. The decay of SIRT7 confers an age-related decline of TLR2‒NF-κB signaling. Although the overexpression of exogenous Sirt7 abrogates skin immune reactivity reduction in aged mice, loss of Sirt7 alleviates the rosacea-like features in mice. Thus, we reveal a SIRT7‒TLR2‒NF-κB axis that can be targeted for the improvement of rosacea.

ETS1 acts as a regulator of human healthy aging via decreasing ribosomal activity.

Adaptation to reduced energy production during aging is a fundamental issue for maintaining healthspan or prolonging life span. Currently, however, the underlying mechanism in long-lived people remains poorly understood. Here, we analyzed transcriptomes of 185 long-lived individuals (LLIs) and 86 spouses of their children from two independent Chinese longevity cohorts and found that the ribosome pathway was significantly down-regulated in LLIs. We found that the down-regulation is likely controlled by ETS1 (ETS proto-oncogene 1), a transcription factor down-regulated in LLIs and positively coexpressed with most ribosomal protein genes (RPGs). Functional assays showed that ETS1 can bind to RPG promoters, while ETS1 knockdown reduces RPG expression and alleviates cellular senescence in human dermal fibroblast (HDF) and embryonic lung fibroblast (IMR-90) cells. As protein synthesis/turnover in ribosomes is an energy-intensive cellular process, the decline in ribosomal biogenesis governed by ETS1 in certain female LLIs may serve as an alternative mechanism to achieve energy-saving and healthy aging.

Increased serum levels of CCL3, CXCL8, CXCL9, and CXCL10 in rosacea patients and their correlation with disease severity.

Rosacea is a common chronic inflammatory skin disease involving millions of patients worldwide. Previous studies have highlighted the upregulation of a variety of chemokines in the skin lesions of both rosacea patient and rosacea-like mouse model. However, the serum levels of these chemokines and their clinical significance have not been explored before. In this study, we aimed at examining the serum levels of a series of chemokines (including CCL2, CCL3, CCL20, CXCL1, CXCL8, CXCL9, CXCL10, and CXCL12) implicated in rosacea and their correlation with disease severity. Bio-Plex Pro Human Chemokine Assays were used to measure the serum levels of these chemokines. Investigator's Global Assessment (IGA) was applied for assessing the papules/pustules of rosacea patients, while persistent erythema was evaluated by the Clinician's Erythema Assessment (CEA). Our results revealed that the serum concentration of CCL3, CXCL8, CXCL9, and CXCL10 were markedly elevated in rosacea patients compared to healthy controls. Among them, the levels of CCL3, CXCL8, and CXCL9 were positively correlated with the IGA score, while serum CXCL9 and CXCL10 were positively related with the CEA score of rosacea patients. What's more, the expression of the corresponding receptors of CCL3 (Ccr1), CXCL8 (Cxcr1 and Cxcr2), CXCL9, and CXCL10 (Cxcr3) were all significantly increased in the skin lesions of rosacea-like mouse model with CXCR2 and CXCR3 highly expressed in rosacea patient skins. Our results indicated that CCL3, CXCL8, CXCL9, and CXCL10 might potentially serve as serum indicators for rosacea and could assist the severity evaluation of disease. Findings in this study would also potentially help to develop new targeted therapies for rosacea in future. © 2022 Japanese Dermatological Association.

Androgen Receptor-Mediated Paracrine Signaling Induces Regression of Blood Vessels in the Dermal Papilla in Androgenetic Alopecia.

Androgenetic alopecia (AGA), also known as male pattern baldness, is associated with androgen and androgen receptor (AR) signaling; however, the pathogenesis of AGA remains largely unknown. In this study, we show that nuclear localization of AR is elevated in the dermal papilla (DP) of balding scalp in patients with AGA. Transcriptome analysis identifies microvascular abnormalities in the DP of balding scalp compared with nonbalding scalp of patients with AGA. We provide further evidence that blood vessels regress in the DP of balding scalp at the early stage of hair follicle miniaturization in AGA development. Consistently, we find that microvascular vessels accumulate around the DP on anagen initiation, and angiogenesis is required for hair regeneration in mice. Mechanistically, we show that AR-mediated paracrine signaling, mainly TGFß signaling, from DP cells induces apoptosis of microvascular endothelial cells in the DP of balding scalp of AGA. These findings define a role of AR-mediated regression of blood vessels in DP in AGA and support the notion that early anti-AR treatment is better than late treatment.

Interaction between body weight status and spicy food consumption on the risk of rosacea: A multi-central, hospital-based, case-control study.

BACKGROUND: No researches about the interaction among the risk factors for rosacea were conducted. Some studies prompted obesity and spicy food may have some common pathways. AIMS: To clarify the relationship between body mass index (BMI) and rosacea, and explore the interaction between BMI and spicy food consumption in rosacea. METHODS: This hospital-based case-control study enrolled 1347 rosacea patients and 1290 healthy subjects. The demographic data and clinical data were collected. The association between BMI and rosacea, and the relative excess risk due to interaction of BMI and spicy food consumption was calculated. RESULTS: No interaction was found between underweight, overweight/obesity, and spicy food consumption with regard to the risk of rosacea, mild-to-moderate rosacea, papulopustular rosacea (PPR), or phymatous rosacea (PhR). And underweight and overweight/obesity were not significant associated with rosacea, mild-to-moderate rosacea, PPR, or PhR (p > 0.05). However, spicy food consumption was significantly interacted with underweight on the risk of erythematotelangiectatic rosacea (ETR), and with overweight/obesity on the risk of severe rosacea. Underweight was associated with increased risk of ETR (adjusted odds ratio [aOR] = 1.91, 95% confidence interval [CI]: 1.21, 3.03) among spicy no users, but the association was attenuated into insignificant level when mixed with spicy food factor (p > 0.05). Among moderated spicy food consumers, overweight/obesity was associated with decreased risk of severe rosacea (aOR = 0.70, 95% CI: 0.50, 0.98), but overweight/obesity was insignificant associated with severe rosacea among spicy no users and heavy spicy food consumers (p > 0.05). CONCLUSIONS: Body weight status alone was not significantly associated with rosacea, but the interaction between body weight status and spicy food consumption is involved in the rosacea.

The association between rosacea and the condition of low tolerance to skincare of the facial skin: a case-control study in China.

BACKGROUND: Patients with rosacea often complained of low tolerance to skincare. AIM: To examine if the preexisted low tolerance to skincare is associated with rosacea the occurrence of the Chinese population. METHODS: A retrospective case-control survey of 997 rosacea cases and 1012 skin-healthy controls was carried out in China. Low tolerance to skincare was evaluated based on the history of facial skin allergic reactions related to skincare in the past 5 years before the onset of rosacea. A comparative analysis was performed between the case and control groups by the chi-square test and the logistic regression analysis. RESULTS: History of facial skin allergic reaction due to skin care products (OR = 5.110, 95% CI = 3.893-6.706) and skin care in beauty salons (OR = 3.002, 95% CI = 1.506-5.981) both presented a positive correlations with the occurrence of rosacea. Facial masks and cosmetics were two of the most common products causing facial allergic reaction. The OR values increased with the increased frequency of allergic reactions related to facial mask and cosmetics. In addition, the history of facial skin allergic reaction had a significantly associated with the severity of self-reported symptoms of rosacea including dryness, burning, stinging and itching. CONCLUSIONS: The condition of low tolerance of the facial skin to skincare was closely associated with the occurrence of rosacea.

N2-Polarized Neutrophils Reduce Inflammation in Rosacea by Regulating Vascular Factors and Proliferation of CD4+ T Cells.

The infiltration of neutrophils is implicated in rosacea, which is a common chronic inflammatory facial disease. This study explores the biological function of neutrophils and their underlying mechanism in rosacea. A rosacea-like mouse model was established to explore the polarization of neutrophils. RNA sequencing was used to investigate the underlying mechanisms. Our results show that neutrophils partly switched to N2 phenotypes in both patients with rosacea and rosacea-like mouse models. The rosacea-like phenotype and inflammation in both a genetic mutation (Genista mice) and the Gr-1 antibody‒induced neutropenia mice were significantly aggravated compared with that in the control groups. In vitro, lipopolysaccharide + IFN-γ and IL4 stimulation of neutrophils successfully induced the N1 and N2 polarization of neutrophils, respectively. Replenishment of N2 neutrophils in the lesions of wild-type and Genista mice ameliorated the rosacea-like phenotype and inflammation. RNA sequencing suggested that N2 neutrophils relieved the rosacea-like phenotype, possibly by regulating the expression of blood circulation‒associated factors, such as ACE, AGTR2, and NOS1. Finally, N2 neutrophils regulated the proliferation of CD4+ lymphocytes, which could explain the remission of inflammation in mice. Our results suggest that N2 polarization of neutrophils in rosacea exerts anti-inflammatory effects by regulating vascular factors and proliferation of CD4+ T cells.

Bioinformatics and Network Pharmacology Identify the Therapeutic Role and Potential Mechanism of Melatonin in AD and Rosacea.

Rosacea is significantly associated with dementia, particularly Alzheimer's disease (AD). However, the common underlying molecular mechanism connecting these two diseases remains limited. This study aimed to reveal the common molecular regulatory networks and identify the potential therapeutic drugs for rosacea and AD. There were 747 overlapped DEGs (ol-DEGs) that were detected in AD and rosacea, enriched in inflammation-, metabolism-, and apoptosis-related pathways. Using the TF regulatory network analysis, 37 common TFs and target genes were identified as hub genes. They were used to predict the therapeutic drugs for rosacea and AD using the DGIdb/CMap database. Among the 113 predicted drugs, melatonin (MLT) was co-associated with both RORA and IFN-γ in AD and rosacea. Subsequently, network pharmacology analysis identified 19 pharmacological targets of MLT and demonstrated that MLT could help in treating AD/rosacea partly by modulating inflammatory and vascular signaling pathways. Finally, we verified the therapeutic role and mechanism of MLT on rosacea in vivo and in vitro. We found that MLT treatment significantly improved rosacea-like skin lesion by reducing keratinocyte-mediated inflammatory cytokine secretion and repressing the migration of HUVEC cells. In conclusion, this study contributes to common pathologies shared by rosacea and AD and identified MLT as an effective treatment strategy for rosacea and AD via regulating inflammation and angiogenesis.