Rosacea pathogenesis, common triggers, and dietary role: The cause, the trigger, and the positive effects of different foods

Signaling pathways and targeted therapy for rosacea

Rosacea is a chronic skin inflammatory disease with a global prevalence ranging from 1% to 20%. It is characterized by facial erythema, telangiectasia, papules, pustules, and ocular manifestations. Its pathogenesis involves a complex interplay of genetic, environmental, immune, microbial, and neurovascular factors. Recent studies have advanced our understanding of its molecular basis, focusing on toll-like receptor (TLR) 2 pathways, LL37 expression, mammalian target of rapamycin (mTOR) activation, interleukin (IL)-17 signaling, transient receptor potential vanilloid (TRPV) functions, and the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathways. LL37-associated signaling pathways, particularly involving TLR2 and mTORC1, are critical in the pathogenesis of rosacea. LL37 interacts with signaling molecules such as extracellular signal-regulated kinases 1 and 2 (ERK1/2), nuclear factor kappa B (NF-κB), inflammasomes, C-X-C motif chemokine ligand 8 (CXCL8), mas-related G-protein-coupled receptor X2 (MRGPRX2)-TRPV4, and vascular endothelial growth factor (VEGF). This interaction activates macrophages, neutrophils, mast cells, and vascular endothelial cells, leading to cytokine release including tumor necrosis factor-alpha (TNF-α), IL-6, IL-1β, C motif chemokine ligand (CCL) 5, CXCL9, and CXCL10. These processes contribute to immune response modulation, inflammation, and angiogenesis in rosacea pathophysiology. The IL-17 signaling pathway also plays a crucial role in rosacea, affecting angiogenesis and the production of inflammatory cytokines. In addition, recent insights into the JAK/STAT pathways have revealed their integral role in inflammatory and angiogenic mechanisms associated with rosacea. Rosacea treatment currently focuses on symptom management, with emerging insights into these molecular pathways providing more targeted and effective therapies. Biological agents targeting specific cytokines, IL-17 inhibitors, JAK inhibitors, and VEGF antagonists are promising for future rosacea therapy, aiming for enhanced efficacy and fewer side effects. This review provides a comprehensive overview of the current knowledge regarding signaling pathways in rosacea and potential targeted therapeutic strategies.

The role of vitamins and nutrients in rosacea

Rosacea is a common inflammatory skin condition displaying symptoms like flushing, erythema, papules, and pustules. Oral antibiotics, despite long-term adverse effects, are often used due to topical treatment limitations, underscoring the need for cost-effective choices like dietary modifications. Our review investigates the role of vitamins and minerals in rosacea, and provides evidence-based recommendations for supplementation and topical treatment of these nutrients for rosacea. An online search was performed on PubMed, Web of Science, Science Direct, Google Scholar, and ClinicalTrials.gov from 1998 to 2023. Included studies were summarized and assessed for quality and relevance in rosacea management. Varied outcomes emerged concerning the impact of essential vitamins and minerals on rosacea treatment. Vitamin A derivatives, specifically oral isotretinoin, demonstrated significant efficacy, with a 90% reduction in lesions, complete remission in 24% of patients, and marked improvement in 57% of patients. Vitamin B3 derivatives, such as topical 1-methylnicotinamide 0.25% and NADH 1%, improved symptoms in 76.4% (26/34) and 80% of patients, respectively. Outcomes for vitamin D, vitamin C, and zinc supplementation varied across studies. However, zinc sulfate solution 5% significantly reduced acne rosacea severity for patients with 40% and 60% exhibiting a moderate or good response, respectively. Omega-3 fatty acids showed significant improvement in alleviating xerophthalmia in 64% of patients with ocular rosacea. Vitamins and minerals hold potential in managing rosacea symptoms, offering a safe and cost-effective alternative or adjunctive treatment option. Currently, there are no established recommendations regarding their supplementation for rosacea. Studies assessing serum levels of vitamins and minerals in relation to rosacea are warranted, as this avenue holds potential for future advancements in the field.

Rosacea treatment with mussel adhesive protein delivered via microneedling: In vivo and clinical studies

BACKGROUND

Rosacea is a prevalent chronic dermatological condition marked by facial inflammation and erythema, significantly compromising the quality of life for affected individuals. Current treatment methods for rosacea are not considered ideal because of the complex etiology of the disease. Mussel adhesive protein (MAP) is a glycoprotein derived from the foot gland of mussels. The protein exhibits anti-inflammatory properties, relieves skin itching, and promotes wound healing.

AIMS

We aimed to explore the feasibility of using MAP administered via microneedle delivery for treating rosacea and the potential molecular mechanism involved.

MATERIALS AND METHODS

The therapeutic effect and mechanism of MAP microneedle delivery in an LL-37-induced rosacea-like mouse model were observed using morphological and histological methods. Twenty-seven patients with erythematotelangiectatic rosacea (ETR) underwent treatment once every 1 month, with three treatments constituting one treatment course. The therapeutic effect was evaluated by comparing the clinical images taken at baseline, after the first treatment course, and after the second treatment course. The red value, CEA, and GFSS score were also calculated.

RESULTS

In response to the microneedle delivery of MAP, innate immunity, inflammatory infiltration, and abnormal neurovascular regulation improved significantly in rosacea-like mice. In the clinical experiments, the microneedle delivery of MAP significantly improved the symptoms of erythema, flushing, and telangiectasia in patients with ETR, and no obvious adverse reactions were observed.

CONCLUSIONS

MAP delivered by microneedling is effective and safe for treating ETR.

Cutaneous neurogenic inflammation mediated by TRPV1-NGF-TRKA pathway activation in rosacea is exacerbated by the presence of Demodex mites

BACKGROUND

Rosacea is a common chronic inflammatory skin condition that is often refractory to treatment, with frequent relapses. Alterations in the skin immunological response and Demodex mite infestation are the primary aetiologic factors targeted for treatment. Transient receptor potential cation channel subfamily V member 1 (TRPV1) is a nociceptive cation channel that plays a role in cutaneous neurogenic pain and can be activated by various rosacea triggers.

OBJECTIVES

We investigated the effects of TRPV1 modulation in rosacea, focussing on Demodex mite colonization and cutaneous neurogenic inflammation.

METHODS

We examined mRNA expression levels according to Demodex population counts. An in vitro study using capsazepine as a TRPV1 antagonist was performed to assess the influence of TRPV1 in keratinocytes. A rosacea-like mouse model was generated by the injection of the 37-amino acid C-terminal cathelicidin peptide (LL37), and changes in the skin, dorsal root ganglion (DRG) and ears were examined.

RESULTS

Increased Demodex mite population counts were associated with increased expression levels of TRPV1, tropomyosin receptor kinase A (TrkA) and nerve growth factor (NGF), and these levels could be reduced by capsazepine treatment in keratinocytes. In an in vivo study, the downstream effects of TRPV1 activation were investigated in the skin, DRG and ears of the rosacea-like mouse model.

CONCLUSIONS

The findings of this study are instrumental for understanding the underlying causes of rosacea and could potentially lead to the development of new treatments targeting the NGF-TrkA-TRPV1 pathway. The identification of this pathway as a therapeutic target could represent a major breakthrough for rosacea research, potentially resulting in more effective and targeted rosacea treatments. This study contributes to an improved understanding of rosacea pathophysiology, which may lead to the development of more effective treatments in the future.

Red-faced lies: a qualitative analysis of online misinformation and conspiracy theories in rosacea

Rosacea is a common chronic inflammatory skin disease with a complex aetiology and major psychological impact, rendering patients susceptible to misinformation. We aimed to assess the content of rosacea-related misinformation online. A formal review of PubMed was performed, using the terms 'rosacea' AND 'misinformation' OR 'disinformation' OR 'conspiracy theory', along with informal Google searches using combinations of these terms, and further targeted searches on Twitter, Facebook, Instagram and TikTok. Key areas of misinformation identified in the search included mislabelling of rosacea as adult acne; falsehoods about rosacea only occurring in older adults or in individuals with lightly pigmented skin; incorrect causes of rosacea such as makeup or diet; and misleading 'cures', some of which may lead to exacerbation of the underlying rosacea. Dermatologists must be aware of the large amount of rosacea misinformation trending online and be prepared to counteract them with evidence to optimize patient care.

Dietary Patterns in Acne and Rosacea Patients-A Controlled Study and Comprehensive Analysis

As the relationship between exposome factors and inflammatory skin diseases is gaining increasing attention, the objective of this study was to investigate dietary patterns among acne and rosacea patients and to establish the disease risk attributable to nutrition. In this cross-sectional, controlled study, patients' dietary habits were assessed via subjective ratings of beneficial and trigger foods, followed by standardized food frequency surveys (FFS). Scores for disease-specific risk stratification based on dietary habits were proposed. Clinical assessments, dermatologic examinations, and laboratory analyses were performed. A total of 296 patients (acne group (AG) n = 120, control group (ACG) n = 32; rosacea group (RG) n = 105, control group (RCG) n = 39) were included. The significant impact of diet on disease severity was self-reported by 80.8% of the AG and 70.5% of the RG. Leading dietary triggers were found in both groups, while beneficial food items were identified more clearly by the AG. FFS revealed significant dietary differences between the AG, RG, and control groups. Disease-specific scores showed greater precision for acne (odds ratio 14.5 AG, 5.5 RG). The AG had higher insulin-like growth factor (IGF)-1 levels correlating with dairy intake (p = 0.006). Overall, this study underlines the influence of diet on acne and rosacea, providing valuable disease-specific scores for dietary risk stratification. Consuming vegetables, legumes, oily fish, olive oil, and nuts, and limiting meat, cheese, and alcohol appear to be beneficial for both acne and rosacea. Future studies can build on these data to further improve preventive and therapeutic strategies.

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.

Differences in clinical characteristics of rosacea across age groups: A retrospective study of 840 female patients

BACKGROUND

Aging remains a common influencing factor for many diseases. Previous studies have shown that age is significantly associated with rosacea among female cases and that the incidence of rosacea increases with age. However, previous studies did not specifically analyze the clinical characteristics of different age groups.

OBJECTIVE

This study aimed to analyze and compare the clinical characteristics of female patients of rosacea among different age groups.

METHODS

We conducted a retrospective study of 840 female rosacea subjects and compared cutaneous features, aggravating factors, systemic diseases, and psychological states across age groups. The patients were divided into three groups according to their age at diagnosis: ≤30 years，31-44 years，and ≥45 years.

RESULTS

In our study, the mean age of subjects was 35.9 ± 10.23 years. The common symptoms included telangiectasia (82.6%), persistent erythema (82.0%), burning/stinging sensation (89.3%), dry sensation (74.0%), and pruritis (41.9%). Hot temperature (89.9%), emotional changes (67.3%), spicy food (55.6%), and sun exposure (50.7%) were the common aggravating factors. Some patients had comorbidities of systemic disorders (20.4%). Of the patients, 48.8% presented with anxiety and 35.2% with depression. The clinical characteristics were found to be significantly different among the different age groups. Middle-aged and older patients (≥45 years) were more likely to have more serious persistent erythema and telangiectasia. And these patients were relatively less affected by some of the influencing factors and had more systemic diseases of the digestive system, endocrine metabolic system, and cardiovascular system (p < 0.05).

CONCLUSION

We revealed the impact of age on the characteristics of rosacea, which indicated that the clinical features of rosacea are more complex and more difficult to treat in females over the age of 45.

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.

Open-Label assessment of the efficacy and tolerability of a skin care regimen for treating subjects with visible and physical symptoms of sensitive skin

BACKGROUND

Sensitive skin is a common concern with 60%-70% of women and 50%-60% of men reporting skin sensitivity and redness. Facial redness is associated with a higher incidence of embarrassment, social anxiety, and diminished quality of life. While there is no cure for sensitive skin, it can be controlled.

AIMS

The objective of this 12-week, open-label clinical trial was to assess the efficacy and tolerability of a topical facial regimen for treating subjects with facial redness and sensitive skin.

PATIENTS/METHODS

Enrolled subjects were healthy male and female individuals, 25-60 years old with Fitzpatrick skin types I-VI who were seeking treatment for moderate or severe facial redness. Subjects were provided with products which were applied each morning and evening. The investigator assessed change in subject appearance using Overall Redness and Global Improvement Scales and subjects rated changes in appearance and tolerability with self-assessment scales.

RESULTS

The mean Overall Redness Scale Score improved by 34% and 25% at Weeks 8 and 12, respectively. There was Mild or Moderate improvement in Global Improvement Scale scores beginning at Week 2 with over 50% achieving Marked improvement by Week 12. All subjects Agreed or Strongly Agreed that their facial redness was less noticeable, their skin appeared less inflamed, overall skin appearance improved, and skin looked and felt healthier at Week 12. The regimen was well-tolerated.

CONCLUSIONS

This study demonstrated a treatment regimen designed to neutralize skin redness and calm inflamed skin was well-tolerated and improved the symptoms of sensitive skin.