Are Demodex mites principal, conspirator, accomplice, witness or bystander in the cause of rosacea?

Correlation between Demodex species in primary and recurrent chalazia

OBJECTIVE

To determine the correlation between the infestation by species of Demodex spp. and the occurrence of primary and recurrent chalazia.

METHODS

Prospective and observational study. Patients with primary or recurrent chalazia were included. Eyelash samples were taken to determine the microscopic presence of Demodex spp. The correlation between the recurrence of the chalazia and the infestation by Demodex spp. mites was determined using Spearman's rank correlation coefficient test.

RESULTS

Sixty-eight adult patients diagnosed with chalazia were included. In 63.2% of the total cases, the presence of one or more parasites of the genus Demodex spp. was documented. In the quantitative parasitological study, it was found that 25% of all cases presented infestation by Demodex spp. defined by an index greater than or equal to 0.5 parasites per eyelash. The most frequently found species was Demodex folliculorum. Of the 14 patients with recurrent chalazia, 50% presented infestation by Demodex spp. and in 91.7% of the cases the infestation was by D. folliculorum. There is a positive, directly proportional correlation between these factors (rθ=+0.665, P<.05). In the group of patients with primary chalazion, only 18.5% presented infestation by Demodex spp., and in 81.6% of these cases it was caused by D. folliculorum. There is a non-statistically significant correlation between these two factors.

CONCLUSION

There is a direct, high and statistically significant correlation between the recurrence of the chalazion and the infestation by Demodex spp., there is no statistically significant correlation between the primary chalazia and the presence of Demodex spp.

Diagnosing Disorders of Facial Erythema

Identification of specific patterns, shades, and intensity of erythema in the skin has always been critical and fundamental to diagnostic accuracy in dermatology. Erythema is often less noticeable in darker skin types. The interplay of inflammation and variance of skin tone contributes to appreciable differences in the clinical appearance of cutaneous disease in darker complexions. In this article, we discuss common disorders that present with facial erythema in skin of color and offer distinguishing features of each disorder to assist the clinician with diagnosing these conditions in the presence of deeply pigmented skin.

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.

Demodex folliculorum (Trombidiformes: Demodicidae) and Demodex brevis Prevalence in an Extreme Environment of Chile

The prevalence of mites of the genus Demodex and their associations with host age, gender, workplace, and comorbid skin and ocular conditions were studied in participants in Antofagasta, Chile, which is in a region with an extreme environment. We examined 680 participants aged 18-88 yr using standardized surface skin biopsies. Among them, Demodex had a prevalence of 13.5 % (95% confidence interval, 10.88-16.17). A slightly higher prevalence was observed in males (51.1%; 95% confidence interval, 40.9-61.3; nonsignificant) and participants in the 69-88 yr age group (50.0%; 95% confidence interval, 23.8-76.2; P < 0.05). Regarding the species involved, Demodex folliculorum was found in 89.1% (CI 82.7-95.5) of cases, while D. brevis was found in the remaining 10.9% of cases. A higher prevalence (25.0% CI 16.1-33.91) was observed in participants who worked indoors in generally enclosed and dust-rich environments (such as theaters, libraries, and administrative offices). There was also a strong association between Demodex prevalence and conjunctival hyperemia, with 35.9% (95% confidence interval, 9.1-35; OR 17.9) of the Demodex positive participants having this pathology compared to 10.3% of the noninfested participants. In summary, the prevalence of Demodex in Antofagasta, Chile (13.5%) was toward the lower end of the range reported among other regions around the world. Environmental factors such as exposure to the sun (including ultraviolet rays) or environmental pollution may affect the mites. In addition, Demodex genetics (related to virulence) and the ocular or skin microbiota may positively or negatively influence infestation and pathology.

From Dysbiosis to Healthy Skin: Major Contributions of Cutibacterium acnes to Skin Homeostasis

Cutibacterium acnes is the most abundant bacterium living in human, healthy and sebum-rich skin sites, such as the face and the back. This bacterium is adapted to this specific environment and therefore could have a major role in local skin homeostasis. To assess the role of this bacterium in healthy skin, this review focused on (i) the abundance of C. acnes in the skin microbiome of healthy skin and skin disorders, (ii) its major contributions to human skin health, and (iii) skin commensals used as probiotics to alleviate skin disorders. The loss of C. acnes relative abundance and/or clonal diversity is frequently associated with skin disorders such as acne, atopic dermatitis, rosacea, and psoriasis. C. acnes, and the diversity of its clonal population, contributes actively to the normal biophysiological skin functions through, for example, lipid modulation, niche competition and oxidative stress mitigation. Compared to gut probiotics, limited dermatological studies have investigated skin probiotics with skin commensal strains, highlighting their unexplored potential.

Effectiveness of benzyl benzoate treatment on clinical symptoms and Demodex density over time in patients with rosacea and demodicosis: a real life retrospective follow-up study comparing low- and high-dose regimens

Background: Patients with rosacea and demodicosis have high facial skin Demodex densities (Dds), which decrease with benzyl benzoate (BB) treatment.Objectives: To evaluate the impact of topical BB (+crotamiton) treatment on Dds and clinical symptoms during prolonged follow-up and to compare low (12% once daily) and high (12% twice daily or 20-24% once daily) BB dose regimens.Methods: This retrospective study included 344 patients (103 rosacea, 241 demodicosis) observed for 7.1 ± 0.5 months. Dds were measured on two consecutive standardized skin surface biopsies and symptoms evaluated using investigator global assessment. Compliance was considered good if patients correctly followed treatment instructions.Results: At final follow-up, in the 248 patients with good compliance, Dd had normalized in 217 (88%) and symptoms cleared in 204 (82%). The high dose was associated with better compliance and faster results than the low-dose. The higher the initial Dd, the longer it took to normalize. In the 96 poorly compliant patients, treatment was less effective and slower.Conclusions: These findings indirectly support a key role of the mite in rosacea and suggest that topical treatment with BB (+crotamiton), especially the higher dose, may be a useful alternative treatment for rosacea as well as for demodicosis.[Formula: see text].

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.

Methods for extraction and ex-vivo experimentation with the most complex human commensal, Demodex spp

Demodex spp. mites are the most complex organisms of the human skin microbiome and were discovered more than 175 years ago, yet only little basic research is published about them. As they can be pathophysiologically relevant ectoparasites associated with rosacea, pityriasis folliculorum, and other inflammatory skin diseases, more research should be encouraged. Being a large microorganism or a tiny animal, there are no established basic methods to handle these mites. Here, we describe techniques enabling the extraction of Demodex mites from human skin, their analysis in different ex-vivo settings, the lysis of their exoskeleton, their preservation by freezing, and observation microscopically using specific fluorescent dyes or their inherent autofluorescence. These procedures should facilitate future Demodex research and fuel further the generation of knowledge. Furthermore it is intended to ultimatively enable the mite's cultivation in vitro and reveal its pathophysiological mechanisms.

Real-life experience on effectiveness and tolerability of topical ivermectin in papulopustular rosacea and antiparasitic effect on Demodex mites

Ivermectin is a drug approved for the treatment of papulopustular rosacea (PPR). Although clinical guidelines recommend the use of ivermectin as the first-line treatment in patients with almost clear and mild rosacea, studies concerning its use on them are lacking. This study investigated the effectiveness and the tolerability of ivermectin in almost clear to severe rosacea and assessed the antiparasitic effect on Demodex mites. This is a retrospective study based on 50 patients affected by PPR and treated with topical ivermectin 1% once daily over 16 weeks. The disease severity, the patient-examined improvement, and the safety assessment of patients were evaluated. Demodex mites were studied with the standardized skin surface biopsy. PPR to all severity achieved a therapeutic success. The number of inflammatory lesions was significantly decreased in almost clear (p < .0001), mild, moderate, and severe (p < .001) forms. A complete remission of inflammatory lesions was achieved by almost clear (p < .001) and mild (p = .005) with 82% with none-to-mild cutaneous adverse events. Thirty-two percent were positive for Demodex mites, and all of them turned negative after 16 weeks. Ivermectin is an effective treatment not only in moderate to severe PPR but also in almost clear/mild rosacea.

The Prevalence of Demodex folliculorum and Demodex brevis in Cylindrical Dandruff Patients

Purpose

To compare the prevalence of and factors associated with Demodex brevis and Demodex folliculorum in patients with cylindrical dandruff (CD group) and healthy controls.

Methods

Eyelashes were taken from 1680 patients with CD and 1700 healthy controls in China from March 2015 to May 2017. All patients underwent a complete eye examination, and Demodex spp. were counted. The prevalence was analyzed according to age, gender, and clinical features.

Results

Mean patient age was 42.93 ± 16.52 (3-88) and 39.4 ± 13.6 (7-81) years old in the CD and healthy control groups, respectively. In the CD and healthy groups, the positive rate for Demodex folliculorum was 27.92% and 8.47%, respectively, while that for Demodex brevis was 31.67% and 6.65%, respectively. In the CD group, the prevalence of Demodex brevis was higher than that of Demodex folliculorum, no matter in the females (33.65% versus 29.01%) or the males (28.54% versus 23.88%) in the CD group. Moreover, the numbers of Demodex folliculorum and Demodex brevis were significantly and positively correlated with age, in both children and old patients (both P < 0.001), as well as with the severity of eyelid congestion (all P < 0.05).

Conclusions

In a large sample population, the prevalence of Demodex brevis and Demodex folliculorum was higher in the CD group than in healthy volunteers. In addition, the severity of eyelid congestion might be exacerbated by the number of Demodex spp., which may therefore provide a good clinical reference and objective guide.

Efficient isolation and observation of the most complex human commensal, Demodex spp

Demodex spp. mites are an often neglected member of the human skin microbiome. Mostly they are commensals, although their pathophysiological role in rosacea, spinulosis folliculorum, and other skin diseases is recognized. Little is known about their life cycle, biology, and physiology. Demodex mites cannot be cultivated in vitro, thereby complicating research immensely. The manual extraction from human sebum is laborious and death can only be detected by surrogate markers like ceased movement or loss of fluorescence. Here we present a new approach for the extraction of larger mite numbers and the hitherto most precise way to detect death. The extraction of mites from sebum and debris by hand can be accelerated by a factor 10 using sucrose gradient centrifugation, which is well tolerated by the mites. Staining with propidium iodide allows for easy identification of dead mites, excluding frail mites that stopped moving, and has no negative effect on overall mite survival. We anticipate our methods to be a starting point for more sophisticated research and ultimately in vitro cultivation of Demodex spp. mites.

Investigation of Demodex folliculorum frequency in patients with polycystic ovary syndrome

Background

Background: Demodex mites are acari that reside in the pilosebaceous unit of the skin and have been associated with skin disorders.

Objective

The objective of this study was to investigate the prevalence of Demodex folliculorum (D. folliculorum) mites in polycystic ovary syndrome patients as well as to examine the relationship between Demodex infestation and the presence of acne and oily or dry skin types in polycystic ovary syndrome patients.

Methods

41 polycystic ovary syndrome patients and 47 non-polycystic ovary syndrome control subjects were enrolled in the study. polycystic ovary syndrome was diagnosed according to the revised 2003 ESHRE/ASRM polycystic ovary syndrome Consensus Workshop Group diagnostic criteria. Microscopic examination of D. folliculorum mites was carried out by standardized skin surface biopsy. The result was considered positive when there were more than 5 mites per cm².

Results

D. folliculorum was positive in 53.7% of the polycystic ovary syndrome patients and 31.9% of the non-polycystic ovary syndrome group (p=0.052). Demodex positivity was significantly associated with acne (p=0.003) and oily skin (p=0.005) in the polycystic ovary syndrome patients but not in the controls.

Study limitation

Our study is limited by the relatively small number of subjects and the observational nature of the study design.

Conclusion

Demodex mites might have a role in acne pathogenesis in patients with polycystic ovary syndrome. Anti-Demodex treatment may increase the response to treatment of acne. Further studies are indicated.

Papulopustular rosacea and rosacea-like demodicosis: two phenotypes of the same disease?

Background

Papulopustular rosacea and rosacea‐like demodicosis have numerous similarities, but they are generally considered as two distinct entities, mainly because the causal role of the Demodex mite in the development of rosacea is not yet widely accepted. Several clinical characteristics are traditionally considered to differentiate the two conditions; for example, papulopustular rosacea is typically characterized by central facial papulopustules and persistent erythema, whereas small superficial papulopustules and follicular scales rather suggest rosacea‐like demodicosis. However, none of these characteristics is exclusive to either entity.

Objective

To explore differences in Demodex densities according to clinical characteristics traditionally associated with these two conditions.

Methods

Retrospective, observational, case–control study of 242 patients with central face papulopustules. Demodex densities were measured on two consecutive standardized skin surface biopsies.

Results

In the whole cohort, Demodex densities were greater in patients with persistent erythema than in those without. In 132 patients without recent treatment or other facial dermatoses, 120 (91%) had persistent erythema, 119 (90%) small superficial papulopustules and 124 (94%) follicular scales; 116 (88%) simultaneously had clinical characteristics traditionally associated with both papulopustular rosacea and rosacea‐like demodicosis. Higher Demodex densities were linked to the presence of follicular scales, but not to papulopustules size, nor to the presence/absence of persistent erythema.

Conclusion

Our observations highlight the difficulty differentiating between these entities and suggest that rosacea‐like demodicosis and papulopustular rosacea should no longer be considered as two separate entities, but rather as two phenotypes of the same disease.

The impact of age, sex, blepharitis, rosacea and rheumatoid arthritis on Demodex mite infection

INTRODUCTION

Two human-specific Demodex species have been described: Demodex folliculorum and Demodex brevis. A medical condition caused by the presence of Demodex is called demodicosis.

MATERIAL AND METHODS

The study material comprised eyelashes collected from 1499 patients.

RESULTS

Demodex sp. infection was revealed in 47% of patients (487 women and 216 men). We determined the following rates of infection by age groups: 1-25 (8% of infected subjects), 26-40 (36%), 41-55 (50%), 56-70 (67%), over 70 (77%). The sex of the subjects was not identified as a factor conducive to infection (p = 0.108), while their age was positively correlated with the risk of infection (p < 0.005). The 1499 study subjects included patients with blepharitis, rosacea, and rheumatoid arthritis. The study investigated the extent to which the above-mentioned conditions affect the risk of Demodex infection. Applying the method of logistic regression, the infection probability was estimated, depending on the age, sex, and comorbidities such as blepharitis, rosacea, and rheumatoid arthritis. Patients suffering from blepharitis were found to have a nearly 2.5-fold higher risk of Demodex infection than those without blepharitis, and the risk for rosacea patients was determined as three-fold higher than that of the general population.

CONCLUSIONS

Blepharitis and rosacea are risk factors for Demodex infection.

The efficacy of tea tree face wash, 1, 2-Octanediol and microblepharoexfoliation in treating Demodex folliculorum blepharitis

PURPOSE

To compare the efficacy of Dr Organic Tea Tree Face Wash, OcuSoft Lids Scrub Plus and the BlephEx™ device at treating of Demodex folliculorum blepharitis.

METHODS

Eighty-six subjects (33 males/36 females) were enrolled in a randomised controlled interventional treatment study. Subjects completed a dry eye symptom questionnaire and were assessed for presence of Demodex folliculorum. Subjects were divided into three groups according to treatment: Dr Organic Tea Tree Face Wash (A) (n=28), OcuSoft Lid Scrub Plus (B) (n=30), or in-house lid scrub with the BlephEx™ device before nightly lid scrubs with OcuSoft Lid Scrub Plus (C) (n=28). Subjects were advised to clean their eyelids nightly for four weeks. Each subject was re-assessed for symptoms and Demodex folliculorum blepharitis after two weeks and four weeks of treatment.

RESULTS

The quantity of Demodex folliculorum was significantly reduced after four weeks of treatment in all three groups (p<0.05). Overall, there was no difference in efficacy between the three treatments (p>0.1). Symptoms reported by subjects were significantly improved after two and four weeks of treatment (p<0.05). Overall, there was no difference in efficacy between the three treatments to reduce symptoms after two or four weeks (p= 0.813 and p=0.646 respectively).

CONCLUSION

All three methods tested have shown good ability to reduce Demodex folliculorum quantity, improve subjective symptoms and help treat Demodex folliculorum blepharitis.

Dual anti-inflammatory and anti-parasitic action of topical ivermectin 1% in papulopustular rosacea

BACKGROUND

Recently, therapy of rosacea with inflammatory lesions (papulopustular) has improved substantially with the approval of topical ivermectin 1% cream. It is assumed to have a dual mode of action with anti-inflammatory capacities and anti-parasitic effects against Demodex, which however has not yet been demonstrated in vivo.

AIM

To find scientific rationale for the dual anti-inflammatory and anti-parasitic mode of action of topical ivermectin 1% cream in patients with rosacea.

METHODS

A monocentric pilot study was performed including 20 caucasion patients with moderate to severe rosacea, as assessed by investigator global assessment (IGA score ≥3) and a Demodex density ≥15/cm² . Patients were treated with topical ivermectin 1% cream once daily (Soolantra^® ) for ≥12 weeks. The density of Demodex mites was assessed with skin surface biopsies. Expression of inflammatory and immune markers was evaluated with RT-PCR and by immunofluorescence staining.

RESULTS

The mean density of mites was significantly decreased at week 6 and week 12 (P < 0.001). The gene expression levels of IL-8, LL-37, HBD3, TLR4 and TNF-α were downregulated at both time points. Reductions in gene expression were significant for LL-37, HBD3 and TNF-α at both follow-up time points and at week 12 for TLR4 (all P < 0.05). Reduced LL-37 expression (P < 0.05) and IL-8 expression were confirmed on the protein level by immunofluorescence staining. All patients improved clinically, and 16 of 20 patients reached therapeutic success defined as IGA score ≤1.

CONCLUSION

Topical ivermectin 1% cream acts by a dual, anti-inflammatory and anti-parasitic mode of action against rosacea by killing Demodex spp. in vivo, in addition to significantly improving clinical signs and symptoms in the skin.

Topical Ivermectin 10 mg/g and Oral Doxycycline 40 mg Modified-Release: Current Evidence on the Complementary Use of Anti-Inflammatory Rosacea Treatments

Rosacea is a common, chronic inflammatory skin disease that can present with a variety of signs and symptoms. The potentially simultaneous occurrence of different signs and symptoms is due to different underlying inflammatory pathways, emphasizing the need for complementary treatment approaches. Topical ivermectin cream (10 mg/g) and systemic, oral anti-inflammatory doxycycline (40 mg modified-release) are both approved for the treatment of papulopustular rosacea (PPR). Whether or not a combined therapeutic approach may be more beneficial than monotherapy for patients with PPR remains to be tested. Here, we summarize underlying inflammatory pathways implicated in rosacea and clarify the impact of these two agents on selective pathways during inflammation, due to specific characteristics of their individual mechanisms of action (MoA). Based on the complementary MoA of doxycycline modified-release and ivermectin, a scientific rationale for a combined therapy targeting inflammatory lesions in rosacea is given. We propose that topical ivermectin cream is a promising new candidate as first-line treatment to target the inflammatory lesions of rosacea, which can be used in combination with systemic doxycycline modified-release to provide an optimal treatment approach considering all inflammatory pathways involved in PPR.

Funding Galderma.