The potential role of microorganisms in the development of rosacea

Therapeutic strategies focusing on immune dysregulation and neuroinflammation in rosacea

Rosacea is a complex inflammatory condition characterized by papulopustular lesions and erythema on the central face for which there is no cure. The development of rosacea is influenced by both external triggers and genetics, but the common pathophysiology is overactivation of the immune system. Here, we review the current data on proinflammatory cytokines and dysregulation of the neurovascular system as targetable components of rosacea. Amelioration of cutaneous and gastrointestinal dysbiosis and other external factors impacts the immune state and has been observed to improve rosacea. While multiple treatments exist, many patients do not achieve their goals for rosacea control and highlights an unmet need for dermatologic care. Current interventions encompass topical/oral drugs, light devices, and avoidance of triggers management. Additional understanding of the underlying pathogenesis may help us develop novel targeted therapeutic strategies to improve rosacea.

The Skin Microbiome and Its Role in Psoriasis: A Review

The skin microbiome is made of various microorganisms, most of which have the function of protecting individuals from harmful pathogens, and they are involved in innate and adaptive immune responses. The skin acts as a physical and immunological barrier against external stimuli, including pathogens and physical damage. Changes in the composition of the skin microbiome can trigger inflammatory processes leading to inflammatory skin diseases in susceptible individuals. Psoriasis (PsO) is a chronic inflammatory disease with a multifactorial etiology, where breakdown of immune tolerance to cutaneous microorganisms is implicated in its pathogenesis. Dysregulation of the microbiome due to genetic and environmental factors plays a significant role in the development of psoriatic disease. Dermatologic conditions such as atopic dermatitis, acne, psoriasis, and rosacea have been associated with intestinal dysbiosis. The skin microbiota composition is crucial for the development of appropriate immune responses, and alterations in the skin microbiome can contribute to changes in physiology and susceptibility to skin diseases or inflammatory conditions. Understanding the microbial settlement of the skin and the network of interactions that occur throughout life is essential for comprehending the pathogenesis of skin diseases and developing innovative treatments. With this article we tried to explore the relationship between the human microbiome and psoriatic disease, shedding light on the functions of the microbiome and the inflammatory disease processes to identify additional therapeutic targets. This review aims to highlight the relationship between skin and gut microbiome functions and inflammatory processes in skin psoriasis and psoriatic arthritis (PsA). The goal is to facilitate future studies on the skin microbiome to identify potential novel therapies for patients with psoriatic disease.

Skin microbiota in health and disease: From sequencing to biology

Microbiota live in a closely regulated interaction with their environment, and vice versa. The presence and absence of microbial entities is greatly influenced by features of the niche in which they thrive. Characteristic of this phenomenon is that different human skin sites harbor niche‐specific communities of microbes. Microbial diversity is considerable, and the current challenge lies in determining which microbes and (corresponding) functionality are of importance to a given ecological niche. Furthermore, as there is increasing evidence of microbial involvement in health and disease, the need arises to fundamentally understand microbiome processes for application in health care, nutrition and personal care products (e.g. diet, cosmetics, probiotics). This review provides a current overview of state‐of‐the‐art sequencing‐based techniques and corresponding data analysis methodology for profiling of complex microbial communities. Furthermore, we also summarize the existing knowledge regarding cutaneous microbiota and their human host for a wide range of skin diseases.

Dynamics Relationship of Phyllosphere and Rhizosphere Bacterial Communities During the Development of Bothriochloa ischaemum in Copper Tailings

Copper mining and the byproducts associated with the industry have led to serious pollution in the Loess Plateau of China. There is a potential in improving the ecological restoration efficiency of such degraded land through combining microbial and plant remediation approaches. However, the community structure and function of phyllosphere and rhizosphere microorganisms and their response to plant development in copper tailings dams are poorly understood. This study investigated the impact of the phyllosphere and rhizosphere microbial communities on Bothriochloa ischaemum during three distinct plant development stages: seedling, tiller, and mature. The relative species abundance and Shannon index of bacterial communities of the rhizosphere during the seedling and tiller stages were distinct from that in the mature stage. Dominant bacteria at the level of phyla, such as Proteobacteria, Cyanobacteria, Actinobacteria, and Bacteroidetes, followed distinct patterns associated with plant development in the phyllosphere, but the predominant bacteria were similar in the rhizosphere. Redundancy analysis showed that aboveground total nitrogen and the carbon and nitrogen ratio of this plant species significantly affected phyllosphere bacterial community structure, whereas soil water content, soil nutrients, electrical conductivity, and salinity significantly affected rhizosphere bacterial community structure. Moreover, keystone phyllosphere and rhizosphere bacterial species differed significantly. This study sheds new light on understanding the dynamic relationship of phyllosphere and rhizosphere bacterial communities during plant development in copper tailings. These results are beneficial to the development and utilization of beneficial microbial communities at different stages of development, which might help to reclaim and stabilize tailings more effectively.

Rosacea is associated with conjoined interactions between physical barrier of the skin and microorganisms: A pilot study

Background

Rosacea is a common condition characterized by transient or persistent central facial erythema, and often papules and pustules. Currently, the role of bacterium in the development and progression of rosacea remains controversial. This study aimed to investigate the difference in the physiological conditions and microorganisms between the lesional and non‐lesional areas of papulopustular rosacea.

Methods

Twenty‐five French patients with papulopustular rosacea were enrolled in this pilot study. Each patient was subjected to clinical assessment, and the skin barrier function was tested in lesional and non‐lesional areas. In addition, samples from the lesional and non‐lesional areas were collected for bacterial culturing.

Results

Of all subjects included in the study, a lower skin conductivity was measured in lesional areas than in non‐lesional areas (43.5 ± 12.4 vs. 57.2 ± 11.6 U, P < .05), and a higher transepidermal water loss (TEWL) value was found in lesional areas than in non‐lesional areas (17.2 ± 5.9 vs. 14.2 ± 4.1 g/(m² h), P < .05). We found a lower TEWL in lesions in rosacea patients with bacterial dysbiosis than in those with bacterial balance (P < .05). In addition, there were significant differences in the skin conductivity and TEWL between lesional and non‐lesional areas in patients with bacterial dysbiosis (P < .001), and no significant differences were seen in patients with bacterial balance (P < .05).

Conclusion

The results of the present study demonstrate that the physiological features of rosacea are closely associated with the interactions between the host and the microorganisms.

Characterization and Analysis of the Skin Microbiota in Rosacea: Impact of Systemic Antibiotics

Systemic antibiotics are extensively used to control the papules and pustules of rosacea. Hence, it is crucial to understand their impact on the rosacea skin microbiota which is thought to be perturbed. The purpose of this study was to compare the makeup and diversity of the skin microbiota in rosacea before and after taking oral antibiotics. We also compared the skin microbiota at baseline according to age and rosacea severity. A longitudinal cohort study was performed on 12 rosacea patients with papules/pustules and no recent use of oral and topical antimicrobials/retinoids. Patients were prescribed oral doxycycline, 100 mg, twice daily for six weeks. Skin areas on the cheek and nose were sampled for 16S ribosomal RNA gene sequencing at baseline, and after six weeks of doxycycline treatment. Eleven females and one male aged 20–79 (median 51) with a median Investigator’s Global Assessment score of 3 (moderate) were enrolled. At baseline, Staphylococcus epidermidis was the most dominant species followed by Cutibacterium acnes (formerly Propionibacterium acnes). In the 60 Over-age group, the prevalence of Cutibacterium acnes was lower than that of the 60 & Under-age group. Rosacea severity increased with age and was associated with a decrease in the relative abundance of Cutibacterium acnes and an increase of Snodgrassella alvi. Across all subjects, antibiotic treatment reduced clinical rosacea grades and was associated with an increase in the relative abundance of Weissella confusa (P = 0.008, 95% CI 0.13% to 0.61%). Bacterial diversity (alpha diversity) was not significantly altered by antibiotics treatment. Principal coordinates analysis showed mild clustering of samples by patient (ANOSIM, Analysis of Similarity, R = 0.119, P = 0.16) and scant clustering with treatment (ANOSIM, R = 0.002; P = 0.5). In conclusion, we believe that rosacea has a unique age-dependent characteristic (i.e., severity). Although we were not able to pinpoint a causative microbiota, our study provides a glimpse into the skin microbiota in rosacea and its modulation by systemic antibiotics.

Clinical picture, diagnosis and treatment of rosacea, complicated by Demodex mites

The article analyzes the clinical picture and course of rosacea in patients with Demodex mites. It presents the advantages of using the method of confocal laser scanning microscopy over the method of light microscopy of facial skin scrapes. The aimes were to study the influence of Demodex mites on the clinical picture and course of rosacea; to compare laboratory and instrumental diagnostic methods for detecting Demodex mites; to evaluate the effectiveness of external therapy aimed at eliminating Demodex mites. 212 people were examined. The study included healthy patients, patients with a diagnosis of rosacea with the presence and absence of Demodex. The presence of Demodex mites was confirmed by two methods of study (light microscopy of skin scrapes and confocal laser scanning in vivo microscopy). Demodex mites promote the development of acute-inflammatory morphological elements, increase the duration of the condition (more than 5 years, P<0.01) and the probability of recurrence (from 1 to 3 relapses in 39.5% of patients, P<0.05), resulting in a decrease in the quality of life of patients (dermatology life quality index is 12.5±4.5, P<0.05). Antiparasitic drug ivermectin, in the form of an external form, at a concentration of 1% has a high therapeutic efficacy (in 93.3% of cases). Demodex folliculorum shows signs of parasitism, while Demodex folliculorum brevis is a saprophyte. The severity of the condition does not depend on the quantitative load of the mites in the scrape. As an antiparasitic drug, it is recommended to use 1% ivertmectin.

Effects of Heavy Metals on Phyllosphere and Rhizosphere Microbial Community of Bothriochloa ischaemum

Copper mining has resulted in severe damage to the ecological environment of mining areas. This study investigated heavy metal distribution in plants and compared the driving factors between aboveground and subsurface microorganisms, as well as the diversity in rhizosphere and non-rhizosphere soil microbial community response to heavy metal transfer factors in a copper tailings dam. We analyzed phyllosphere and soil microbial community using high-throughput sequencing and denaturing gradient gel electrophoresis, respectively. Although we detected chromium in aboveground and subsurface of Bothriochloa ischaemum specimens, no chromium was detected in soil. Total nitrogen was negatively correlated to the carbon and nitrogen ratios of plants and soil, respectively, while the total sulfur was negatively correlated to cadmium in roots. On the contrary, soil sulfur was positively correlated to cadmium in soil. Moreover, soil sulphur was the main influencing factor on the soil bacterial community, while ammonium nitrogen, total nitrogen, and zinc were the driving factors of fungi diversity in non-rhizosphere soil. Fungi diversity in the rhizosphere was significantly correlated to phosphatase, and fungi diversity in the non-rhizosphere was significantly correlated to sucrose enzymes. The transfer factor of lead was negatively correlated to rhizosphere fungi diversity, and the transfer factor of copper was significantly correlated to non-rhizosphere bacterial diversity. Results from this study may offer some scientific reference for the improvement of plant-microbe remediation efficiency. At the same time, this study could provide an ecological basis for further studies on soil ecosystem restoration and degradation mechanisms that are associated with copper tailings dams.

Rosacea and Helicobacter pylori: links and risks

Rosacea is a chronic skin disease characterized by facial erythema and telangiectasia. Despite the fact that many hypotheses have been proposed, its etiology remains unknown. In the present review, the possible link and clinical significance of Helicobacter pylori in the pathogenesis of rosacea are being sought. A PubMed and Google Scholar search was performed using the terms “rosacea”, “H.pylori”, “gastrointestinal disorders and H.pylori”, “microorganisms and rosacea”, “pathogenesis and treatment of rosacea”, and “risk factors of rosacea”, and selected publications were studied and referenced in text. Although a possible pathogenetic link between H. pylori and rosacea is advocated by many authors, evidence is still interpreted differently by others. We conclude that further studies are needed in order to fully elucidate the pathogenesis of rosacea.

Association study of Demodex bacteria and facial dermatoses based on DGGE technique

The role of bacteria is unclear in the facial skin lesions caused by Demodex. To shed some light on this issue, we conducted a case-control study comparing cases with facial dermatoses with controls with healthy skin using denaturing gradient gel electrophoresis (DGGE) technique. The bacterial diversity, composition, and principal component were analyzed for Demodex bacteria and the matched facial skin bacteria. The result of mite examination showed that all 33 cases were infected with Demodex folliculorum (D. f), whereas 16 out of the 30 controls were infected with D. f, and the remaining 14 controls were infected with Demodex brevis (D. b). The diversity analysis showed that only evenness index presented statistical difference between mite bacteria and matched skin bacteria in the cases. The composition analysis showed that the DGGE bands of cases and controls were assigned to 12 taxa of 4 phyla, including Proteobacteria (39.37-52.78%), Firmicutes (2.7-26.77%), Actinobacteria (0-5.71%), and Bacteroidetes (0-2.08%). In cases, the proportion of Staphylococcus in Firmicutes was significantly higher than that in D. f controls and D. b controls, while the proportion of Sphingomonas in Proteobacteria was significantly lower than that in D. f controls. The between-group analysis (BGA) showed that all the banding patterns clustered into three groups, namely, D. f cases, D. f controls, and D. b controls. Our study suggests that the bacteria in Demodex should come from the matched facial skin bacteria. Proteobacteria and Firmicutes are the two main taxa. The increase of Staphylococcus and decrease of Sphingomonas might be associated with the development of facial dermatoses.

Cutaneous rosacea: a thorough overview of pathogenesis, clinical presentations, and current recommendations on management

The review summarizes and systemizes available international data on the pathogenesis, clinical manifestations and current recommendations for the management of rosacea patients.

New developments in the treatment of rosacea - role of once-daily ivermectin cream

Rosacea is a chronic dermatological disorder with a variety of clinical manifestations localized largely to the central face. The unclear etiology of rosacea fosters therapeutic difficulty; however, subtle clinical improvement with pharmacologic treatments of various drug categories suggests a multifactorial etiology of the disease. Factors that may contribute to disease pathogenesis include immune abnormality, vascular abnormality, neurogenic dysregulation, presence of cutaneous microorganisms, UV damage, and skin barrier dysfunction. The role of ivermectin in the treatment of rosacea may be as an anti-inflammatory and anti-parasitic agent targeting Demodex mites. In comparing topical ivermectin and metronidazole, ivermectin was more effective; this treatment modality boasted more improved quality of life, reduced lesion counts, and more favorable participant and physician assessment of disease severity. Patients who received ivermectin 1% cream had an acceptable safety profile. Ivermectin is efficacious in decreasing inflammatory lesion counts and erythema.

Extraintestinal manifestations of Helicobacter pylori: A concise review

Helicobacter pylori (H. pylori) infection has been clearly linked to peptic ulcer disease and some gastrointestinal malignancies. Increasing evidence demonstrates possible associations to disease states in other organ systems, known as the extraintestinal manifestations of H. pylori. Different conditions associated with H. pylori infection include those from hematologic, cardiopulmonary, metabolic, neurologic, and dermatologic systems. The aim of this article is to provide a concise review of the evidence that supports or refutes the associations of H. pylori and its proposed extraintestinal manifestations. Based on data from the literature, PUD, mucosal associated lymphoid tumors lymphoma, and gastric adenocarcinoma has well-established links. Current evidence most supports extraintestinal manifestations with H. pylori in immune thrombocytopenic purpura, iron deficiency anemia, urticaria, Parkinson’s, migraines and rosacea; however, there is still plausible link with other diseases that requires further research.

Rosacea and rhinophyma

Rosacea is a common and chronic inflammatory cutaneous disease with unknown etiology. The pathophysiology of rosacea is still poorly understood. Epidemiological studies indicate a genetic component, but a rosacea gene has not been detected yet. Recent molecular studies propose that an altered innate immune response is involved in the pathogenesis of the rosacea disease. Signs of rosacea are indicated by the presence of characteristic facial or ocular inflammation involving both the vascular and tissue stroma. A wide range of drug options is available for the treatment of rosacea, including several topical ones (metronidazole, antibiotics, azelaic acid, benzoyl peroxide, sulfacetamide/sulfur, retinoids) and oral ones (mainly tetracyclines, metronidazole, macrolides, isotretinoin). This review highlights the recent clinical and pathophysiological developments concerning rosacea.

New insights into rosacea pathophysiology: a review of recent findings

Rosacea is a common, chronic inflammatory skin disease of poorly understood origin. Based on its clinical features (flushing, chronic inflammation, fibrosis) and trigger factors, a complex pathobiology involving different regulatory systems can be anticipated. Although a wealth of research has shed new light over recent years on its pathophysiology, the precise interplay of the various dysregulated systems (immune, vascular, nervous) is still poorly understood. Most authors agree on 4 major clinical subtypes of rosacea: erythematotelangiectatic rosacea, papulopustular rosacea, phymatous rosacea, and ocular rosacea. Still, it needs to be elucidated whether these subtypes develop in a consecutive serial fashion or if any subtypes may occur individually as part of a syndrome. Because rosacea often affects multiple family members, a genetic component is also suspected, but the genetic basis of rosacea remains unclear. During disease manifestation and early stage, the innate immune system and neurovascular dysregulation seem to be driving forces in rosacea pathophysiology. Dissection of major players for disease progression and in advanced stages is severely hampered by the complex activation of the innate and adaptive immune systems, enhanced neuroimmune communication, profound blood vessel and possibly lymphatic vessel changes, and activation of almost every resident cell in the skin. This review discusses some of the recent findings and aims to build unifying hypotheses for a modern understanding of rosacea pathophysiology.

Management of facial erythema of rosacea: what is the role of topical α-adrenergic receptor agonist therapy?

Several more recent advances have led to a better understanding of the pathophysiologic mechanisms involved in rosacea and therapeutic modalities used for treatment. Although the clinical features may vary among patients, there are some unifying mechanisms that appear to relate to the more common presentations of rosacea. Both neurovascular dysregulation and augmented immune detection and response appear to play central roles that lead to many of the signs and symptoms of rosacea. Diffuse central facial erythema is a very common finding that intensifies during flares and persists to varying degrees between flares. This background of facial redness occurs secondary to vasodilation and fixed vascular changes that develop over time. Physical modalities are commonly used to treat the erythema that persists as a result of fixed changes in superficial cutaneous vasculature that do not remit after treatment with agents whose mechanisms are active primarily against some of the inflammatory processes operative in rosacea (ie metronidazole, azelaic acid, tetracyclines). As enlarged superficial cutaneous vessels that contribute to the fixed background facial redness of rosacea remain vasoactive to sympathetic nervous system innervation, topical α-adrenergic receptor agonists, namely brimonidine and oxymetazoline, are currently under evaluation for the treatment of facial erythema of rosacea. This article focuses on the clinical differentiation of facial erythema of rosacea and its management.

Rosacea: pathophysiology and management principles

This article presents an overview of the pathophysiology, epidemiology, and clinical presentations of rosacea. It also presents the therapeutic spectrum for effective management of this challenging and often confusing clinical entity.

Potential role of Demodex mites and bacteria in the induction of rosacea

Rosacea is a common dermatological condition that predominantly affects the central regions of the face. Rosacea affects up to 3 % of the world's population and a number of subtypes are recognized. Rosacea can be treated with a variety of antibiotics (e.g. tetracycline or metronidazole) yet no role for bacteria or microbes in its aetiology has been conclusively established. The density of Demodex mites in the skin of rosacea patients is higher than in controls, suggesting a possible role for these mites in the induction of this condition. In addition, Bacillus oleronius, known to be sensitive to the antibiotics used to treat rosacea, has been isolated from a Demodex mite from a patient with papulopustular rosacea and a potential role for this bacterium in the induction of rosacea has been proposed. Staphylococcus epidermidis has been isolated predominantly from the pustules of rosacea patients but not from unaffected skin and may be transported around the face by Demodex mites. These findings raise the possibility that rosacea is fundamentally a bacterial disease resulting from the over-proliferation of Demodex mites living in skin damaged as a result of adverse weathering, age or the production of sebum with an altered fatty acid content. This review surveys the literature relating to the role of Demodex mites and their associated bacteria in the induction and persistence of rosacea and highlights possible therapeutic options.

Cathelicidin LL-37: an antimicrobial peptide with a role in inflammatory skin disease

Chronic inflammatory skin diseases such as atopic dermatitis, psoriasis or rosacea are very common. Although their exact pathogenesis is not completely understood all three diseases are characterized by dysregulation of cutaneous innate immunity. Cathelicidin LL-37 is an important effector molecule of innate immunity in the skin and atopic dermatitis, psoriasis or rosacea show defects in cathelicidin expression, function or processing. In atopic dermatitis, cathelicidin induction might be disturbed resulting in defective antimicrobial barrier function. In contrast, psoriasis is characterized by overexpression of cathelicidin. However to date it is unclear whether pro- or anti-inflammatory functions of cathelicidin predominate in lesional skin in psoriasis. In rosacea, cathelicidin processing is disturbed resulting in peptide fragments causing inflammation, erythema and telangiectasias. In this review, the current evidence on the role of cathelicidin LL-37 in the pathogenesis of inflammatory skin diseases will be outlined. As cathelicidin LL-37 might also serve as a future treatment target potential novel treatment strategies for those diseases will be discussed.

Rosacea: The cytokine and chemokine network

Rosacea is one of the most common dermatoses of adults. Recent studies have improved our understanding of the pathophysiology of rosacea. Current concepts suggest that known clinical trigger factors of rosacea such as UV radiation, heat, cold, stress, spicy food, and microbes modulate Toll-like receptor signaling, induce reactive oxygen species, as well as enhance antimicrobial peptide and neuropeptide production. Downstream of these events cytokines and chemokines orchestrate an inflammatory response that leads to the recruitment and activation of distinct leukocyte subsets and induces the characteristic histopathological features of rosacea. Here we summarize the current knowledge of the cytokine and chemokine network in rosacea and propose pathways that may be of therapeutic interest.

Clinical, cellular, and molecular aspects in the pathophysiology of rosacea

Rosacea is a chronic inflammatory skin disease of unknown etiology. Although described centuries ago, the pathophysiology of this disease is still poorly understood. Epidemiological studies indicate a genetic component, but a rosacea gene has not been identified yet. Four subtypes and several variants of rosacea have been described. It is still unclear whether these subtypes represent a "developmental march" of different stages or are merely part of a syndrome that develops independently but overlaps clinically. Clinical and histopathological characteristics of rosacea make it a fascinating "human disease model" for learning about the connection between the cutaneous vascular, nervous, and immune systems. Innate immune mechanisms and dysregulation of the neurovascular system are involved in rosacea initiation and perpetuation, although the complex network of primary induction and secondary reaction of neuroimmune communication is still unclear. Later, rosacea may result in fibrotic facial changes, suggesting a strong connection between chronic inflammatory processes and skin fibrosis development. This review highlights recent molecular (gene array) and cellular findings and aims to integrate the different body defense mechanisms into a modern concept of rosacea pathophysiology.