Unveiling the Role of Endoplasmic Reticulum Stress Pathways in Canine Demodicosis

Canine demodicosis is a prevalent skin disease caused by overpopulation of a commensal species of Demodex mite, yet its precise cause remains unknown. Research suggests that T-cell exhaustion, increased immunosuppressive cytokines, induction of regulatory T cells and increased expression of immune checkpoint inhibitors may contribute to its pathogenesis. This study aimed to gain a deeper understanding of the molecular changes occurring in canine demodicosis using mass spectrometry and pathway enrichment analysis. The results indicate that endoplasmic reticulum stress promotes canine demodicosis through regulation of three linked signalling pathways: eIF2, mTOR, and eIF4 and p70S6K. These pathways are involved in the modulation of Toll-like receptors, most notably TLR2, and have been shown to play a role in the pathogenesis of skin diseases in both dogs and humans. Moreover, these pathways are also implicated in the promotion of immunosuppressive M2 phenotype macrophages. Immunohistochemical analysis, utilising common markers of dendritic cells and macrophages, verified the presence of M2 macrophages in canine demodicosis. The proteomic analysis also identified immunological disease, organismal injury and abnormalities and inflammatory response as the most significant underlying diseases and disorders associated with canine demodicosis. This study demonstrates that Demodex mites, through ER stress, unfolded protein response and M2 macrophages contribute to an immunosuppressive microenvironment, thereby assisting in their proliferation.

ER stress: an emerging regulator in GVHD development

Allogeneic hematopoietic cell transplantation (allo-HCT) is a promising therapeutic option for hematologic malignancies. However, the clinical benefits of allo-HCT are limited by the development of complications including graft-versus-host disease (GVHD). Conditioning regimens, such as chemotherapy and irradiation, which are administered to the patients prior to allo-HCT, can disrupt the endoplasmic reticulum (ER) homeostasis, and induce ER stress in the recipient's cells. The conditioning regimen activates antigen-presenting cells (APCs), which, in turn, activate donor cells, leading to ER stress in the transplanted cells. The unfolded protein response (UPR) is an evolutionarily conserved signaling pathway that manages ER stress in response to cellular stress. UPR has been identified as a significant regulatory player that influences the function of various immune cells, including T cells, B cells, macrophages, and dendritic cells (DCs), in various disease progressions. Therefore, targeting the UPR pathway has garnered significant attention as a promising approach for the treatment of numerous diseases, such as cancer, neurodegeneration, diabetes, and inflammatory diseases. In this review, we summarize the current literature regarding the contribution of ER stress response to the development of GVHD in both hematopoietic and non-hematopoietic cells. Additionally, we explore the potential therapeutic implications of targeting UPR to enhance the effectiveness of allo-HCT for patients with hematopoietic malignancies.

The role of macrophages in rosacea: implications for targeted therapies

Introduction

Rosacea, a widespread chronic skin condition, may be influenced by macrophages, key immune cells in the skin, although their exact role is not yet fully understood. This review delves into the function of macrophages, their potential contribution to rosacea pathogenesis, current treatments, and promising macrophage-targeted therapies. It concludes by identifying knowledge gaps and potential areas for future rosacea research.

Method

Leveraging systematic and narrative literature review techniques, we conducted a comprehensive search of databases such as PubMed, Embase, and Web of Science. Utilizing keywords like "rosacea" and "macrophages", we targeted English articles from the last 5 years (2018-2023). We manually checked reference lists of relevant articles for additional studies. We included only articles emphasizing macrophages' role in rosacea and/or the development of related therapies and published within the specified timeframe.

Results

The systematic search of electronic databases yielded a total of 4,263 articles. After applying the inclusion and exclusion criteria, 156 articles were selected for inclusion in this review. These articles included original research studies, review articles, and clinical trials that focused on the role of macrophages in rosacea and/or the development of macrophage-targeted therapies for the disease. The selected articles provided a comprehensive and up-to-date overview of the current state of research on macrophages in rosacea, including their function in the skin, the potential mechanisms through which they may contribute to rosacea pathogenesis, and the current treatments and therapies available for the disease. Additionally, the articles identified gaps in knowledge regarding the role of macrophages in rosacea and suggested potential areas for future research.

Conclusion

This literature review emphasizes the important role that macrophages, vital immune cells in the skin, may play in the pathogenesis of rosacea, a common chronic inflammatory skin disorder. The selected studies suggest potential mechanisms by which these cells might contribute to rosacea progression, although these mechanisms are not yet fully understood. The studies also spotlight current rosacea treatments and illuminate the promising potential of new macrophage-focused therapies. Despite these insights, significant gaps persist in our understanding of the precise role of macrophages in rosacea. Future research in this area could provide further insights into the pathogenesis of rosacea and contribute to the development of more effective, targeted therapeutic strategies.

Exploring the Pathogenesis and Mechanism-Targeted Treatments of Rosacea: Previous Understanding and Updates

Rosacea is a chronic inflammatory skin disease characterized by recurrent erythema, flushing, telangiectasia, papules, pustules, and phymatous changes in the central area of the face. Patients with this condition often experience a significant negative impact on their quality of life, self-esteem, and overall well-being. Despite its prevalence, the pathogenesis of rosacea is not yet fully understood. Recent research advances are reshaping our understanding of the underlying mechanisms of rosacea, and treatment options based on the pathophysiological perspective hold promise to improve patient outcomes and reduce incidence. In this comprehensive review, we investigate the pathogenesis of rosacea in depth, with a focus on emerging and novel mechanisms, and provide an up-to-date overview of therapeutic strategies that target the diverse pathogenic mechanisms of rosacea. Lastly, we discuss potential future research directions aimed at enhancing our understanding of the condition and developing effective treatments.

Increased Risk of Glaucoma in Patients with Rosacea: A Nationwide Population-Based Cohort Study

Rosacea is a chronic inflammatory skin disorder associated with various ocular manifestations. However, little is known about the association between rosacea and glaucoma. This study aimed to determine the risk of glaucoma in patients with rosacea. This nationwide population-based retrospective cohort study enrolled 1056 individuals with rosacea and 10,440 age- and sex-matched controls without rosacea from the Korean National Health Insurance System (NHIS) database from 2002 to 2015. The incidence rate of glaucoma was 1215.4 per 100,000 person-years (PYs) in patients with rosacea and 741.3 per 100,000 PYs in patients without rosacea. A significantly higher cumulative incidence probability of glaucoma was observed in patients with rosacea than in non-rosacea controls (p = 0.0004). Rosacea was associated with an increased risk of developing glaucoma (adjusted hazard ratio [aHR], 1.659; 95% confidence interval [CI], 1.245-2.211) compared to those without rosacea. In subgroup analysis, increased risk of glaucoma was observed in patients with rosacea younger than 50 years (aHR, 1.943; 95% CI, 1.305-2.893), females (aHR, 1.871; 95% CI, 1.324-2.644), and patients with hypertension (aHR, 1.561; 95% CI, 1.037-2.351) compared to those without rosacea. Rosacea is associated with an increased risk of developing glaucoma. Proper screening for glaucoma should be conducted in rosacea patients younger than 50 years, females, and patients with hypertension to better control the disease and prevent vision loss from glaucoma.

Host Defense Peptides in Nutrition and Diseases: A Contributor of Immunology Modulation

Host defense peptides (HDPs) are primary components of the innate immune system with diverse biological functions, such as antibacterial ability and immunomodulatory function. HDPs are produced and released by immune and epithelial cells against microbial invasion, which are widely distributed in humans, animals, plants, and microbes. Notably, there are great differences in endogenous HDP distribution and expression in humans and animals. Moreover, HDP expression could be regulated by exogenous substances, such as nutrients, and different physiological statuses in health and disease. In this review, we systematically assessed the regulation of expression and mechanism of endogenous HDPs from nutrition and disease perspectives, providing a basis to identify the specificity and regularity of HDP expression. Furthermore, the regulation mechanism of HDP expression was summarized systematically, and the differences in the regulation between nutrients and diseases were explored. From this review, we provide novel ideas targeted the immune regulation of HDPs for protecting host health in nutrition and practical and effective new ideas using the immune regulation theory for further research on protecting host health from pathogenic infection and excessive immunity diseases under the global challenge of the antibiotic-abuse-induced series of problems, including food security and microbial resistance.

Characterization of rosacea patients in Tohoku area of Japan: Retrospective study of 340 rosacea cases

Rosacea is a chronic inflammatory skin disease with facial redness and acne-like papules and pustules. The characteristics and background of rosacea patients in Japan have not been well documented. In this study, we retrospectively collected the medical information of rosacea patients, and investigated the background, complications, exacerbating factors, and status of allergy. Between January 2010 and December 2020, 431 cases were diagnosed as rosacea or rosacea-like dermatitis. We selected 340 patients, in which we could confirm telangiectasia on facial skin. Females and males numbered 266 and 74, respectively. The average age of the first visit was 51.5 years, and the youngest and oldest were 11 and 88 years old. Among 340 cases, 323 had erythematotelangiectatic rosacea, 97 papulopustular rosacea, 20 phymatous rosacea presenting as rhinophyma, and four had symptoms of ocular rosacea. The most common complication was hay fever (93 individuals, 27.4%), and 66 (19.4%) had a medical history of contact dermatitis. Temperature differences (141 individuals, 41.5%) were the most common exacerbating factor followed by sunlight exposure (60 individuals, 17.6%). Seventy-eight individuals received allergen-specific immunoglobulin (Ig)E tests, and IgE for cedar was the most frequently observed (46 individuals, 59.0%). High frequencies of IgE for Dermatophagoides pteronyssinus or D. farinae (33 individuals, 42.3%) and house dust I (31 individuals, 39.7%) suggested that environmental conditions at home would affect rosacea symptoms. Since the facial skin is exposed to environmental stimuli every moment, this retrospective observation suggested the importance of the daily lifestyle guidance as well as medical treatments.

Serum IL-17 levels in patients with rosacea

BACKGROUND

Rosacea is a chronic inflammatory skin disease characterized with increased serum and tissue inflammatory mediators. IL-17 is a well-known inflammatory mediator that plays important roles in pathogenesis of inflammatory skin diseases. Previous studies reported that Th17 pathway is activated in rosacea and IL-17, one of Th17 signature cytokines, is elevated in tissue samples of rosacea patients.

OBJECTIVES

The aim of this study was to investigate serum IL-17 levels in rosacea patients and to study its relationship with disease characteristics.

METHODS

Sixty patients diagnosed with rosacea and 60 healthy controls were included in the study. Serum IL-17 concentrations were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The mean serum IL-17 level was 8.03 pg/mL (SD = 1.47) in rosacea patients and 7.37 pg/mL (Sd = 1.19) in controls. Serum IL-17 levels were significantly higher in rosacea (p = 0.002). Serum IL-17 levels were similar among patients with erythematotelangiectatic (ET) and papulopustular (PP) rosacea (8.02 vs 8.06, p = 0.83). Serum IL-17 levels did not correlate with rosacea severity (p = 0.59, r = 0.07 in ET rosacea; p = 0.88, r = 0.02 in PP rosacea), age of onset (p = 0.58, r = -0.07), and disease duration (p = 0.37, r = -0.11). Primary features and global assessments did not correlate with serum IL-17 levels (all p > 0.05). Among secondary features, edema showed a significant negative correlation with serum IL-17 concentrations (p = 0.037, r = -0.26).

CONCLUSIONS

Our study showed increased serum IL-17 levels in rosacea patients and a significant correlation between IL-17 concentrations and secondary features of the disease suggesting IL-17 may contribute to pathogenesis of rosacea and may be a new target for rosacea treatment.

TLR4-mediated pyroptosis in human hepatoma-derived HuH-7 cells induced by a branched-chain polyunsaturated fatty acid, geranylgeranoic acid

A branched-chain polyunsaturated fatty acid, geranylgeranoic acid (GGA; C_20:4), which is an endogenous metabolite derived from the mevalonate pathway in mammals, has been reported to induce cell death in human hepatoma cells. We have previously shown that the lipid-induced unfolded protein response (UPR) is an upstream cellular process for an incomplete autophagic response that might be involved in GGA-induced cell death. Here, we found that Toll-like receptor 4 (TLR4)-mediated pyroptosis in HuH-7 cells occurred by GGA treatment. The TLR4-specific inhibitor VIPER prevented both GGA-induced cell death and UPR. Knockdown of the TLR4 gene attenuated GGA-induced cell death significantly. Upon GGA-induced UPR, caspase (CASP) 4 (CASP4) was activated immediately and gasdermin D (GSDMD) was translocated concomitantly to the plasma membrane after production of the N-terminal fragment of GSDMD. Then, cellular CASP1 activation occurred following a second gradual up-regulation of the intracellular Ca²⁺ concentration, suggesting that GGA activated the inflammasome. Indeed, the mRNA levels of NOD-like receptor family pyrin domain containing 3 (NLRP3) and interleukin-1 β (IL1B) genes were up-regulated dramatically with translocation of cytoplasmic nuclear factor-κB (NF-κB) to nuclei after GGA treatment, indicating that GGA induced priming of the NLRP3 inflammasome through NF-κB activation. GGA-induced up-regulation of CASP1 activity was blocked by either oleic acid, VIPER, MCC950 (a selective inhibitor of the NLRP3 inflammasome), or CASP4-specific inhibitor peptide cotreatment. Pyroptotic cell death was also confirmed morphologically by bleb formation in time-series live cell imaging of GGA-treated cells. Taken together, the present results strongly indicate that GGA causes pyroptotic cell death in human hepatoma-derived HuH-7 via TLR4 signalling.

Identification of novel candidate genes in rosacea by bioinformatic methods

BACKGROUND

Rosacea is a chronic inflammatory skin disease whose psychological consequences severely affect patient's quality of life.

OBJECTIVE

To identify candidate genes of rosacea for potential development of new target therapies.

METHODS

Gene Expression Omnibus datasets were retrieved to obtain differentially expressed genes (DEGs) between rosacea patients and healthy controls. Gene ontology (GO) analyses were used to identify functions of candidate genes. Related signaling pathways of DEGs were analyzed using Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene set enrichment analysis. Protein-protein interaction (PPI) networks were applied using search tools for the retrieval of interacting genes/proteins and modulations involving PPI networks were evaluated with use of the MCODE app.

RESULTS

Samples from 19 rosacea patients and 10 healthy controls of dataset GSE65914 were enrolled. A total of 215 DEGs, 115 GO terms and 6 KEGG pathways were identified. A total of 182 nodes and 456 edges were enriched in PPI networks. Maximal clusters showed 15 central nodes and 96 edges. The toll-like receptor (TLR) signaling pathway was the most significant pathway detected and 5 DEGs were identified as candidate genes which included TLR2, C-C motif chemokine (CCL) 5, C-X-C motif chemokine ligand (CXCL) 9, CXCL10 and CXCL11. The results were verified in rosacea patients with use of real-time polymerase chain reaction and immunohistochemistry. Cell-type enrichment analysis revealed 8 lymphocytes that were enriched in rosacea patients.

CONCLUSIONS

The results suggest that both innate and adaptive immune responses were involved in the etiology of rosacea. Five DEGs in the TLR signaling pathway may serve as potential therapeutic target genes.

Association between Rosacea and Cardiovascular Diseases and Related Risk Factors: A Systematic Review and Meta-Analysis

BACKGROUND

Rosacea is a common inflammatory skin disorder. Several studies, but not all, have suggested a high prevalence of cardiovascular diseases (CVDs) in rosacea patients. This study is aimed at investigating the association between rosacea and CVDs and related risk factors.

METHODS

We performed a literature search through PubMed, Embase, and Web of Science databases, from their respective inception to December 21, 2019. Two reviewers independently screened the articles, extracted data, and performed analysis, following the PRISMA guidelines. Odds ratios (OR) or standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated for outcomes. The included studies' quality was evaluated using the Newcastle Ottawa Scale (NOS).

RESULTS

The final meta-analysis included ten studies. The pooled analysis found no association between rosacea prevalence and the incidence of CVDs (OR 0.97; 95% CI 0.86-1.10). Rosacea was found to be significantly associated with several risk factors for CVDs (OR 1.17; 95% CI 1.05-1.31), including hypertension (OR 1.17; 95% CI 1.02-1.35), dyslipidemia (OR 1.34; 95% CI 1.00-1.79), and metabolic syndrome (OR 1.72; 95% CI 1.09-2.72). However, no association was found between rosacea and diabetes mellitus (OR 0.98; 95% CI 0.82-1.16). Among the biological parameters, a significant association was found between rosacea and total cholesterol (SMD = 0.40; 95% CI = -0.00, 0.81; p < 0.05), low-density lipoprotein cholesterol (SMD = 0.28; 95% CI = 0.01, 0.56; p < 0.05), and C-reactive protein (CRP) (SMD = 0.25; 95% CI = 0.10, 0.41; p < 0.05). We found no association between rosacea and high-density lipoprotein cholesterol (SMD = 0.00; 95% CI = -0.18, 0.18; p = 0.968) or triglycerides (SMD = 0.10; 95% CI = -0.04, 0.24; p = 0.171).

CONCLUSIONS

Although no significant association was found between rosacea and CVDs, rosacea was found to be associated with several of related risk factors. Patients with rosacea should pay more attention to identifiable CVD risk factors, especially those related to inflammatory and metabolic disorders.

Insights into the role of endoplasmic reticulum stress in skin function and associated diseases

Endoplasmic reticulum (ER) stress is a mechanism that allows the protection of normal cellular functions in response to both internal perturbations, such as accumulation of unfolded proteins, and external perturbations, for example redox stress, UVB irradiation, and infection. A hallmark of ER stress is the accumulation of misfolded and unfolded proteins. Physiological levels of ER stress trigger the unfolded protein response (UPR) that is required to restore normal ER functions. However, the UPR can also initiate a cell death program/apoptosis pathway in response to excessive or persistent ER stress. Recently, it has become evident that chronic ER stress occurs in several diseases, including skin diseases such as Darier's disease, rosacea, vitiligo and melanoma; furthermore, it is suggested that ER stress is directly involved in the pathogenesis of these disorders. Here, we review the role of ER stress in skin function, and discuss its significance in skin diseases.

Nuclear Factor Kappa-B Is Enriched in Eyelid Specimens of Rosacea: Implications for Pathogenesis and Therapy

PURPOSE

To assess the role of nuclear factor kappa-B (NFKB) in cutaneous specimens of rosacea and unaffected tissue.

METHODS

Immunohistochemical staining was performed for the activated, phosphorylated variant of NFKB (pNFKB) in eyelid specimens of rosacea (n = 12) and normal, healthy tissue (n = 12). The numbers of positively staining cells/40× microscopic field were counted across 5 consecutive fields. Additionally, quantitative Western blotting was carried out for pNFKB and NFKB in specimens of rosacea (n = 15) and normal controls (n = 14). Statistical comparisons were performed via a dedicated software package.

RESULTS

The mean number of cells/40× microscopic field that stained positively for pNFKB was 18.4 (standard deviation = 15.3) for control patients and 39.3 (standard deviation = 16.9) for rosacea patients, and the difference between the 2 groups was statistically significant (P = .0024). On Western blotting, the mean ratios of pNFKB:NFKB for control and rosacea patients measured 0.58 (standard deviation = 0.81) and 3.11 (standard deviation = 3.53), respectively. The 2 groups were statistically significantly different (P = .0002).

CONCLUSIONS

The activated form of NFKB is enriched in rosacea, indicating a role for this pathway in the pathogenesis of this disease. Interference with NFKB signaling may represent a novel therapy for rosacea as clinical agents become available. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

eIF2 alpha phosphorylation alleviates UVA-induced HO-1 expression in mouse epidermal cells

Ultraviolet A (UVA) irradiation is a potential environmental stressor, which contributes to inflammation, photoaging, and carcinogenesis. UVA causes endoplasmic reticulum stress, hence phosphorylates the α subunit of eIF2. Meanwhile, UVA also induces expression of haem oxygenase-1 (HO-1) and nuclear factor erythroid-derived two related factor 2 (Nrf2) in human skin cells. In mouse JB6 cell, we found high dose UVA could change cell morphology, cause cell viability loss. UVA irradiation activated phosphorylation of eIF2α and Nrf2-HO-1 pathway in a dose-dependent manner. Besides, modulation of eIF2α phosphorylation status could alter expression pattern of Nrf2-HO-1 signalling. Salubrinal, a selective inhibitor of eIF2α dephosphorylation, increased the S phase in cell cycle of JB6 cells after UVA irradiation, suggesting phosphorylation status of eIF2α may affect cellular homeostasis under UVA irradiation. The study directed to further acknowledge about the relationship of UVA-induced eIF2α phosphorylation and Nrf2-HO-1 pathway, which may play a role in phototherapy and photo protection.

ATF4 Involvement in TLR4 and LOX-1-Induced Host Inflammatory Response to Aspergillus fumigatus Keratitis

Purpose

Activating transcription factor 4 (ATF4) is induced by various stressors. Here, we investigated the expression of ATF4 in the host inflammatory response to Aspergillus fumigatus (A. fumigatus) keratitis.

Methods

A. fumigatus keratitis mouse models developed by intrastromal injection as well as corneal epithelium scratching were examined daily with a slit lamp microscope for corneal opacification and ulceration. Subsequent in vitro experimentation was carried out in human corneal epithelial cells (HCECs) as well as THP-1 macrophages infected with A. fumigatus. Inhibitors, including CLI-095, Poly (I), SCH772984, and SP600125, were used to assess the role of proteins like toll-like receptor 4 (TLR4), lectin-type oxidized LDL receptor 1 (LOX-1), extracellular signal-regulated kinases (ERK1/2), and c-Jun N-terminal kinase (JNK) in ATF4 expression as a response to A. fumigatus infection. This assessment was made in both mouse models and HCECs using western blot.

Results

Compared to the controls, ATF4 was increased in corneas from two kinds of A. fumigatus keratitis models at 3 days after infection. ATF4 expression was upregulated with A. fumigatus conidia both in HCECs and THP-1 macrophages 16 hours after stimulation. Furthermore, ATF4 expression in response to A. fumigatus infection was shown to be dependent on TLR4 and LOX-1 expression, and ERK1/2 and JNK contributed to the expression of ATF4 in response to A. fumigatus.

Conclusion

Our results clearly indicate that ATF4 was involved in the host antifungal immune response to A. fumigatus keratitis; expression was found to be dependent on TLR4, LOX-1 expression, and MAPKs pathway.

Thickness of carotid intima and epicardial fat in rosacea: a cross-sectional study

Background

Rosacea is a chronic facial skin disease associated with excessive inflammatory response to various triggers. Although some studies have supported the increased risk of cardiovascular diseases in rosacea, it has not been completely accepted.

Objective

We aimed to investigate epicardial fat thickness and carotid intima-media thickness as cardiovascular risk predictors in rosacea patients.

Methods

We conducted a cross-sectional study including 40 rosacea patients and 40 controls. Demographic data, epicardial fat thickness, carotid intima-media thickness, lipid parameters, biochemical parameters, presence of insulin resistance, and presence of metabolic syndrome of the participants were recorded.

Results

Forty rosacea patients (31 female and 9 male) and 40 controls (30 female and 10 male) were enrolled in the study. Rosacea patients had significantly higher epicardial fat thickness and carotid intima-media thickness volumes than controls (P<0.001). In the multivariate logistic regression analysis, epicardial fat thickness was independently related to presence of rosacea (P<0.001, OR=13.31). In the multiple linear regression analysis, the epicardial fat thickness was independently associated with rosacea (β= 0.47, P<0.001), carotid intima-media thickness (β= 0.36, P<0.001), and systolic blood pressure (β=0.19, P=0.015) and the carotid intima-media thickness was independently associated with epicardial fat thickness (β= 0.6, P<0.001). The epicardial fat thickness levels were correlated with carotid intima-media thickness (r=0.63, P<0.001), LDL (r=0.23, P=0.037), systolic blood pressure (r=0.45, P<0.001), and diastolic blood pressure levels (r=0.37, P=0.001). The carotid intima-media thickness levels were correlated with epicardial fat thickness (r=0.63, P<0.001), systolic blood pressure (r=0.04, P<0.001), and diastolic blood pressure levels (r=0.27, P=0.016).

Study limitations

The small number of participants.

Conclusions

Examination and follow-up of rosacea patients for cardiovascular diseases may be recommended practices.

Friends or Foes? Host defense (antimicrobial) peptides and proteins in human skin diseases

Host defense peptides/proteins (HDPs), also known as antimicrobial peptides/proteins (AMPs), are key molecules in the cutaneous innate immune system. AMPs/HDPs historically exhibit broad-spectrum killing activity against bacteria, enveloped viruses, fungi and several parasites. Recently, AMPs/HDPs were shown to have important biological functions, including inducing cell proliferation, migration and differentiation; regulating inflammatory responses; controlling the production of various cytokines/chemokines; promoting wound healing; and improving skin barrier function. Despite the fact that AMPs/HDPs protect our body, several studies have hypothesized that these molecules actively contribute to the pathogenesis of various skin diseases. For example, AMPs/HDPs play crucial roles in the pathological processes of psoriasis, atopic dermatitis, rosacea, acne vulgaris, systemic lupus erythematosus and systemic sclerosis. Thus, AMPs/HDPs may be a double-edged sword, promoting cutaneous immunity while simultaneously initiating the pathogenesis of some skin disorders. This review will describe the most common skin-derived AMPs/HDPs (defensins, cathelicidins, S100 proteins, ribonucleases and dermcidin) and discuss the biology and both the positive and negative aspects of these AMPs/HDPs in skin inflammatory/infectious diseases. Understanding the regulation, functions and mechanisms of AMPs/HDPs may offer new therapeutic opportunities in the treatment of various skin disorders.

Rosacea: Molecular Mechanisms and Management of a Chronic Cutaneous Inflammatory Condition

Rosacea is a chronic cutaneous inflammatory disease that affects the facial skin. Clinically, rosacea can be categorized into papulopustular, erythematotelangiectatic, ocular, and phymatous rosacea. However, the phenotypic presentations of rosacea are more heterogeneous. Although the pathophysiology of rosacea remains to be elucidated, immunologic alterations and neurovascular dysregulation are thought to have important roles in initiating and strengthening the clinical manifestations of rosacea. In this article, we present the possible molecular mechanisms of rosacea based on recent laboratory and clinical studies. We describe the genetic predisposition for rosacea along with its associated diseases, triggering factors, and suggested management options in detail based on the underlying molecular biology. Understanding the molecular pathomechanisms of rosacea will likely aid toward better comprehending its complex pathogenesis.