Colonization with superantigen-producing Staphylococcus aureus is associated with increased severity of atopic dermatitis

Investigating Distinct Skin Microbial Communities and Skin Metabolome Profiles in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disorder influenced by genetic predisposition, environmental factors, immune dysregulation, and skin barrier dysfunction. The skin microbiome and metabolome play crucial roles in modulating the skin's immune environment and integrity. However, their specific contributions to AD remain unclear. We aimed to investigate the distinct skin microbial communities and skin metabolic compounds in AD patients compared to healthy controls (HCs). Seven patients with AD patients and seven HCs were enrolled, from whom skin samples were obtained for examination. The study involved 16S rRNA metagenomic sequencing and bioinformatics analysis as well as the use of gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) to detect metabolites associated with AD in the skin. We observed significant differences in microbial diversity between lesional and non-lesional skin of AD patients and HCs. Staphylococcus overgrowth was prominent in AD lesions, while Cutibacterium levels were decreased. Metabolomic analysis revealed elevated levels of several metabolites, including hypoxanthine and glycerol-3-phosphate in AD lesions, indicating perturbations in purine metabolism and energy production pathways. Moreover, we found a positive correlation between hypoxanthine and glycerol-3-phosphate and clinical severity of AD and Staphylococcus overgrowth. These findings suggest potential biomarkers for monitoring AD severity. Further research is needed to elucidate the causal relationships between microbial dysbiosis, metabolic alterations, and AD progression, paving the way for targeted therapeutic interventions.

Extracellular Vehicles from Commensal Skin Malassezia restricta Inhibit Staphylococcus aureus Proliferation and Biofilm Formation

The colonizing microbiota on the body surface play a crucial role in barrier function. Staphylococcus aureus (S. aureus) is a significant contributor to skin infection, and the utilization of colonization resistance of skin commensal microorganisms to counteract the invasion of pathogens is a viable approach. However, most studies on colonization resistance have focused on skin bacteria, with limited research on the resistance of skin fungal communities to pathogenic bacteria. Extracellular vehicles (EVs) play an important role in the colonization of microbial niches and the interaction between distinct strains. This paper explores the impact of Malassezia restricta (M. restricta), the fungus that dominates the normal healthy skin microbiota, on the proliferation of S. aureus by examining the distribution disparities between the two microorganisms. Based on the extraction of EVs, the bacterial growth curve, and biofilm formation, it was determined that the EVs of M. restricta effectively suppressed the growth and biofilm formation of S. aureus. The presence of diverse metabolites was identified as the primary factor responsible for the growth inhibition of S. aureus, specifically in relation to glycerol phospholipid metabolism, ABC transport, and arginine synthesis. These findings offer valuable experimental evidence for understanding microbial symbiosis and interactions within healthy skin.

The Skin Barrier and Moisturization: Function, Disruption, and Mechanisms of Repair

BACKGROUND

The anatomic layers of the skin are well-defined, and a functional model of the skin barrier has recently been described. Barrier disruption plays a key role in several skin conditions, and moisturization is recommended as an initial treatment in conditions such as atopic dermatitis. This review aimed to analyze the skin barrier in the context of the function model, with a focus on the mechanisms by which moisturizers support each of the functional layers of the skin barrier to promote homeostasis and repair.

SUMMARY

The skin barrier is comprised of four interdependent layers - physical, chemical, microbiologic, and immunologic - which maintain barrier structure and function. Moisturizers target disruption affecting each of these four layers through several mechanisms and were shown to improve transepidermal water loss in several studies. Occlusives, humectants, and emollients occlude the surface of the stratum corneum (SC), draw water from the dermis into the epidermis, and assimilate into the SC, respectively, in order to strengthen the physical skin barrier. Acidic moisturizers bolster the chemical skin barrier by supporting optimal enzymatic function, increasing ceramide production, and facilitating ideal conditions for commensal microorganisms. Regular moisturization may strengthen the immunologic skin barrier by reducing permeability and subsequent allergen penetration and sensitization.

KEY MESSAGES

The physical, chemical, microbiologic, and immunologic layers of the skin barrier are each uniquely impacted in states of skin barrier disruption. Moisturizers target each of the layers of the skin barrier to maintain homeostasis and facilitate repair.

Oral and Topical Probiotics and Postbiotics in Skincare and Dermatological Therapy: A Concise Review

The skin microbiota is a pivotal contributor to the maintenance of skin homeostasis by protecting it from harmful pathogens and regulating the immune system. An imbalance in the skin microbiota can lead to pathological conditions such as eczema, psoriasis, and acne. The balance of the skin microbiota components can be disrupted by different elements and dynamics such as changes in pH levels, exposure to environmental toxins, and the use of certain skincare products. Some research suggests that certain probiotic strains and their metabolites (postbiotics) may provide benefits such as improving the skin barrier function, reducing inflammation, and improving the appearance of acne-prone or eczema-prone skin. Consequently, in recent years probiotics and postbiotics have become a popular ingredient in skincare products. Moreover, it was demonstrated that skin health can be influenced by the skin-gut axis, and imbalances in the gut microbiome caused by poor diet, stress, or the use of antibiotics can lead to skin conditions. In this way, products that improve gut microbiota balance have been gaining attention from cosmetic and pharmaceutical companies. The present review will focus on the crosstalk between the SM and the host, and its effects on health and diseases.

Skin Microbiome in Prurigo Nodularis

Prurigo nodularis (PN) is a chronic condition characterized by the presence of nodular lesions accompanied by intense pruritus. The disease has been linked to several infectious factors, but data on the direct presence of microorganisms in the lesions of PN are scarce. The aim of this study was to evaluate the diversity and composition of the bacterial microbiome in PN lesions by targeting the region V3-V4 of 16S rRNA. Skin swabs were obtained from active nodules in 24 patients with PN, inflammatory patches of 14 patients with atopic dermatitis (AD) and corresponding skin areas of 9 healthy volunteers (HV). After DNA extraction, the V3-V4 region of the bacterial 16S rRNA gene was amplified. Sequencing was performed using the Illumina platform on the MiSeq instrument. Operational taxonomic units (OTU) were identified. The identification of taxa was carried out using the Silva v.138 database. There was no statistically significant difference in the alpha-diversity (intra-sample diversity) between the PN, AD and HV groups. The beta-diversity (inter-sample diversity) showed statistically significant differences between the three groups on a global level and in paired analyses. Staphylococcus was significantly more abundant in samples from PN and AD patients than in controls. The difference was maintained across all taxonomic levels. The PN microbiome is highly similar to that of AD. It remains unclear whether the disturbed composition of the microbiome and the domination of Staphylococcus in PN lesions may be the trigger factor of pruritus and lead to the development of cutaneous changes or is a secondary phenomenon. Our preliminary results support the theory that the composition of the skin microbiome in PN is altered and justify further research on the role of the microbiome in this debilitating condition.

NOD2 Agonism Counter-Regulates Human Type 2 T Cell Functions in Peripheral Blood Mononuclear Cell Cultures: Implications for Atopic Dermatitis

Atopic dermatitis (AD) is known as a skin disease; however, T cell immunopathology found in blood is associated with its severity. Skin Staphylococcus aureus (S. aureus) and associated host-pathogen dynamics are important to chronic T helper 2 (Th2)-dominated inflammation in AD, yet they remain poorly understood. This study sought to investigate the effects of S. aureus-derived molecules and skin alarmins on human peripheral blood mononuclear cells, specifically testing Th2-type cells, cytokines, and chemokines known to be associated with AD. We first show that six significantly elevated Th2-related chemokine biomarkers distinguish blood from adult AD patients compared to healthy controls ex vivo; in addition, TARC/CCL17, LDH, and PDGF-AA/AB correlated significantly with disease severity. We then demonstrate that these robust AD-associated biomarkers, as well as associated type 2 T cell functions, are readily reproduced from healthy blood mononuclear cells exposed to the alarmin TSLP and the S. aureus superantigen SEB in a human in vitro model, including IL-13, IL-5, and TARC secretion as well as OX-40-expressing activated memory T cells. We further show that the agonism of nucleotide-binding oligomerization domain-containing protein (NOD)2 inhibits this IL-13 secretion and memory Th2 and Tc2 cell functional activation while inducing significantly increased pSTAT3 and IL-6, both critical for Th17 cell responses. These findings identify NOD2 as a potential regulator of type 2 immune responses in humans and highlight its role as an endogenous inhibitor of pathogenic IL-13 that may open avenues for its therapeutic targeting in AD.

Immunomodulatory Role of Staphylococcus aureus in Atopic Dermatitis

Staphylococcus aureus is a gram-positive bacterium commonly found on humans, and it constitutes the skin microbiota. Presence of S. aureus in healthy individuals usually does not pose any threat, as the human body is equipped with many mechanisms to prevent pathogen invasion and infection. However, colonization of S. aureus has been correlated with many healthcare-associated infections, and has been found in people with atopic diseases. In atopic dermatitis, constant fluctuations due to inflammation of the epidermal and mucosal barriers can cause structural changes and allow foreign antigens and pathogens to bypass the first line of defense of the innate system. As they persist, S. aureus can secrete various virulence factors to enhance their survival by host invasion and evasion mechanisms. In response, epithelial cells can release damage-associated molecular patterns, or alarmins such as TSLP, IL-25, IL-33, and chemokines, to recruit innate and adaptive immune cells to cause inflammation. Until recently, IL-36 had been found to play an important role in modulating atopic dermatitis. Secretion of IL-36 from keratinocytes can activate a Th2 independent pathway to trigger symptoms of allergic reaction resulting in clinical manifestations. This mini review aims to summarize the immunomodulatory roles of S. aureus virulence factors and how they contribute to the pathogenesis of atopic diseases.

Characterization of Distinct Microbiota Associated with Scalp Dermatitis in Patients with Atopic Dermatitis

Recent studies have focused on the role of skin microbiota in the pathogenesis of atopic dermatitis (AD). Among the various clinical phenotypes of AD, scalp dermatitis is a commonly observed clinical feature of AD. However, little is known about the pathogenesis of scalp dermatitis in AD. Hence, the aim of this study was to identify the distinct microbiota associated with scalp dermatitis in patients with AD. Using scalp swab samples from 10 patients with AD and 10 healthy controls, this study characterized the scalp microbiota in patients with AD via V3–V4 regions of the 16S rRNA gene sequencing for bacterial identification, and ITS2 gene sequencing for fungal identification. Among bacterial genera, Staphylococcus was the most abundant in AD than in healthy controls, whereas Cutibacterium was the most abundant species in the healthy controls. The most predominant scalp fungal microbiota was Malassezia both in AD and healthy controls, while a higher diversity of non-Malassezia fungi was observed in AD than in healthy controls. The study findings indicate the dysbiosis of scalp microbiota in AD and highlight the potential biomarker role of specific microbiota in AD on the scalp dermatitis.

Gene Expression Profile Analyses of the Skin Response of Balb/c-Nu Mice Model Injected by Staphylococcus aureus

Background

Pathogenesis and persistence of many skin diseases are related to Staphylococcus aureus (S. aureus) colonization. S. aureus infection can cause varying degrees of changes in cell gene expression, resulting in complex changes in cell phenotype and finally changes in cell life activities.

Materials and Methods

The transcriptomes of healthy and Staphylococcus aureus (S. aureus)-infected murine skin tissues were analyzed. We identified 638 differentially expressed genes (DEGs) in the infected tissues compared to the control samples, of which 324 were upregulated and 314 were downregulated, following the criteria of P < 0.01 and |log₂FC| > 3. The DEGs were functionally annotated by Gene Ontology (GO), KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway and the protein–protein interaction (PPI) network analyses.

Results

The upregulated DEGs were mainly enriched in GO terms, such as response to stimulus, immune system process and signal transduction, as well as in the complement and coagulation cascade pathway. Thus, S. aureus infection likely activates these pathways to limit the influx of neutrophils and prevent skin damage. Four clusters were identified in the PPI network, and the major hubs were mainly related to cell cycle and proliferation, and mostly downregulated. The expression levels of Nox4, Mmrn1, Mcm5, Msx1 and Fgf5 mRNAs were validated by qRT-PCR and found to be consistent with the RNA-Seq data, confirming a strong correlation between the two approaches.

Conclusion

The identified genes and pathways are potential drug targets for treating skin inflammation caused by S. aureus and should be investigated further.

The effectiveness of antibacterial therapeutic clothing based on silver or chitosan as compared with non-antibacterial therapeutic clothing in patients with moderate to severe atopic dermatitis (ABC trial): study protocol for a pragmatic randomized controlled trial

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease that affects 10 to 20% of children and between 2 and 15% of the adults in Western Europe. Since 2000, therapeutic clothing or functional textiles based on silver or chitosan as antibacterial agents were introduced for AD. These agents aim to reduce skin colonization with Staphylococcus (S.) aureus. Increased colonization with S. aureus is correlated with increased AD severity. The antimicrobial effects of silver and chitosan have been demonstrated before. At this point, there is insufficient evidence for the effectiveness of antibacterial therapeutic clothing in patients with AD.

METHODS

This is a pragmatic randomized controlled double-blind multi-center trial comparing the effectiveness of antibacterial therapeutic clothing based on silver or chitosan as compared with non-antibacterial therapeutic clothing in patients with moderate to severe AD. A total of 165 participants, aged 0 to 80, diagnosed with moderate to severe AD are included. The study is performed in the Erasmus MC University Medical Center, University Medical Center Groningen, University Medical Center Utrecht, Amsterdam University Medical Centers, and St. Antonius Hospital Nieuwegein. Patients will be randomized 1:1:1 into one of the three intervention groups: group A will receive therapeutic clothing without antimicrobial agents, group B will receive microbial growth reducing therapeutic clothing based on chitosan, and group C will receive antimicrobial clothing based on silver. All therapeutic clothing is to be worn at night during the 12-month intervention period. Usual care is continued. The primary objective is to assess the effectiveness of antibacterial clothing (silver and chitosan group) as compared to non-antibacterial clothing assessed with the Eczema Area and Severity Index at 12 months compared to baseline. Secondary outcomes include between-group differences in physician- and patient-reported outcome measures, topical therapy use, S. aureus skin colonization, and safety. Data will be collected at baseline and after 1 month, 3 months, 6 months, and 12 months. A cost-effectiveness analysis will be performed.

DISCUSSION

This trial will provide data on the effectiveness, cost-effectiveness, and safety of antibacterial therapeutic clothing for patients with AD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04297215. Registered on 5 March 2020.

A review of the mechanisms of keratinocytes damage caused by Staphylococcus aureus infection in patients with atopic dermatitis

The dysregulation of skin microflora in patients with atopic dermatitis (AD) has become a research hotspot in recent years. Metagenomic studies have shown that microbial diversity is decreased, whereas the Staphylococcus aureus infection is increased in AD. Keratinocytes are the primary barrier against the invasion of external pathogenic microorganisms. Staphylococcus aureus infection can abnormally activate innate and adaptive immune responses in keratinocytes, resulting in a vicious cycle between Staphylococcus aureus infection and AD. This article reviews the mechanisms of inflammatory damage of keratinocytes induced by Staphylococcus aureus infection in patients with AD, providing a theoretical basis for the study of new targeted drugs. This review also suggests for the management of Staphylococcus aureus infection in patients with AD.

Zinc oxide nanoparticles prevent multidrug resistant Staphylococcus-induced footpad dermatitis in broilers

The current experiment was designed to evaluate the effects of dietary supplementations of zinc oxide nanoparticles (ZONPs) on some behavioural, performance, welfare and histopathological changes in broilers exposed to multidrug resistant Staphylococcus aureus (MRSA)-induced footpad dermatitis (FPD). Eighty-four male Indian River (IR) broilers were randomly allotted to six different dietary treatments as follows: C-ve, C+ve, 10, 20, 30 and 40 ppm ZONPs from 7 to 49d of age. At day 28, broilers (n = 70) were sub-cutaneously injected with 0.5 ml of saline containing 5.3 × 107 CFU/ml of S. aureus (MRSA) in each metatarsal foot pad. Control (non-infected) broilers were given 0.5 ml of saline (n = 14). Results clarified that non-infected birds and ZONPs-fed birds had significantly higher standing and feeding activities and lower resting activities in comparison with the infected group. Also, the S. aureus infected group had significantly lower body weight gain (BWG) and higher feed conversion ratio (FCR) than the non-infected group. In addition, the non-infected birds and ZONPs groups had significantly lower object crossing and tonic immobility times (TI) and gait scores (GS) in comparison with the S. aureus group. Only ZONPs 30, 40 ppm and non-infected groups had a significantly higher latency to lie time (LLT) and lower serum cortisol level in comparison with the S. aureus group. Moreover, there were significant changes in the gross lesion score and histopathological lesions between the different groups. In conclusion, the dietary supplementation of ZONPs can reduce S. aureus-induced negative effects of FPD in broilers.

Nasal Colonization by Staphylococci and Severity of Atopic Dermatitis

BACKGROUND

Skin colonization by Staphylococcus aureus (SA) correlates with increased severity of atopic dermatitis (AD). The role of nasal SA carriage and coagulase-negative staphylococci (CNSs) in AD is unclear.

OBJECTIVE

The aim of this study was to assess the influence of colonization of lesional/nonlesional skin and the anterior nares by SA and CNSs on AD severity in 63 adult patients.

METHODS

Disease severity was assessed with SCORAD index. The total immunoglobulin E (IgE) concentration was determined using the enzyme-linked immunosorbent assay method. The prevalence and abundance of staphylococci were assessed with the combination of bacterial culture and mass spectrometry.

RESULTS

The prevalence values of SA within the skin (lesional/nonlesional) and anterior nares were 79.4%/61.9% and 69.8%, respectively (vs 5.6% and 13.9%, respectively in controls, P < 0.0001). The carriage of CNSs in all niches was associated with lower mean IgE concentration (1164.66 ± 1010.36 vs 1762.99 ± 1059.15, P < 0.0213; 1166.9 ± 1006.4 vs 2152.7 ± 759.2, P < 0.0063; 1022 ± 1100 vs 1925 ± 880.8, P < 0.0044, respectively). The abundance of SA correlated with the extent of skin lesions and total IgE (ρ = 0.42, P = 0.0007; ρ = 0.488, P < 0.0001; ρ = 0.312, P < 0.2; and ρ = 0.402, P = 0.0007; ρ = 0.403, P < 0.002; ρ = 0.287, P < 0.03, respectively).

CONCLUSIONS

Atopic dermatitis severity correlates with both cutaneous and nasal colonization by SA. Staphylococcus aureus seems to promote TH2-type response, whereas CNS probably limits this process. Preventive measures within the anterior nares should be considered for AD patients.

Colonization With Staphylococcus aureus in Atopic Dermatitis Patients: Attempts to Reveal the Unknown

Atopic dermatitis (AD) patients are massively colonized with Staphylococcus aureus (S. aureus) in lesional and non-lesional skin. A skin infection may become systemic if left untreated. Of interest, the incidence of multi-drug resistant S. aureus (MRSA) in AD patients is higher as compared to a healthy population, which makes treatment even more challenging. Information on the specific genetic background of S. aureus accompanying and/or causing AD flares would be of great importance in terms of possible treatment option development. In this review, we summarized the data on the prevalence of S. aureus in general in AD skin, and the prevalence of specific clones that might be associated with flares of eczema. We put our special interest in the presence and role of staphylococcal enterotoxins as important virulence factors in the epidemiology of AD-derived S. aureus. Also, we summarize the present and potentially useful future anti-staphylococcal treatment.

Methicillin-resistant Staphylococcus aureus from infected skin lesions present several virulence genes and are associated with the CC30 in Brazilian children with atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease and colonization by Staphylococcus aureus may affect up to 100% of these patients. Virulent and resistant isolates can worsen AD patient clinical condition and jeopardize the treatment. We aimed to detect virulence genes and to evaluate the biofilm production of S. aureus isolates from infected skin lesions of children with AD. Methicillin resistance was detected by phenotypic and molecular tests and the virulence genes were detected by PCR. Biofilm formation was assessed by bacterial growing on microtiter plates and later stained with safranin. Genotyping was performed by Pulsed-Field Gel Electrophoresis and Multilocus Sequence Typing. Among 106 AD patients, 55 (51.8%) had developed S. aureus cutaneous infections and 23 (41.6%) were methicillin-resistant (MRSA). All 55 isolates carried the fnbA, hla, icaA, sasG, and seu genes, and more than 70% presented cna, eap, ebpS, hlg, and pvl genes. Clonal complex (CC) 30 was the main lineage found (34.5%), especially among MRSA isolates (52.2%). The egc cluster and the bbp gene were significantly the most frequent in MRSA isolates and in USA1100/ST30/CC30 lineage. Most of the isolates (74.5%) were non-biofilm producers and many of them only started to produce it in the presence of fibrinogen. There was no significant association between S. aureus isolates features and the AD severity. This study demonstrated a high frequency of CC30 MRSA isolates presenting several virulence genes in infected skin lesions of AD children in Brazil, that may influence the severity of the disease and the treatments required.

Staphylococcus aureus binds to the N-terminal region of corneodesmosin to adhere to the stratum corneum in atopic dermatitis

Staphylococcus aureus colonizes the skin of the majority of patients with atopic dermatitis (AD), and its presence increases disease severity. Adhesion of S. aureus to corneocytes in the stratum corneum is a key initial event in colonization, but the bacterial and host factors contributing to this process have not been defined. Here, we show that S. aureus interacts with the host protein corneodesmosin. Corneodesmosin is aberrantly displayed on the tips of villus-like projections that occur on the surface of AD corneocytes as a result of low levels of skin humectants known as natural moisturizing factor (NMF). An S. aureus mutant deficient in fibronectin binding protein B (FnBPB) and clumping factor B (ClfB) did not bind to corneodesmosin in vitro. Using surface plasmon resonance, we found that FnBPB and ClfB proteins bound with similar affinities. The S. aureus binding site was localized to the N-terminal glycine-serine-rich region of corneodesmosin. Atomic force microscopy showed that the N-terminal region was present on corneocytes containing low levels of NMF and that blocking it with an antibody inhibited binding of individual S. aureus cells to corneocytes. Finally, we found that S. aureus mutants deficient in FnBPB or ClfB have a reduced ability to adhere to low-NMF corneocytes from patients. In summary, we show that FnBPB and ClfB interact with the accessible N-terminal region of corneodesmosin on AD corneocytes, allowing S. aureus to take advantage of the aberrant display of corneodesmosin that accompanies low NMF in AD. This interaction facilitates the characteristic strong binding of S. aureus to AD corneocytes.

Nanoparticles for treatment of bovine Staphylococcus aureus mastitis

Staphylococcus aureus (S. aureus) is one of the most important zoonotic bacterial pathogens, infecting human beings and a wide range of animals, in particular, dairy cattle. Globally. S. aureus causing bovine mastitis is one of the biggest problems and an economic burden facing the dairy industry with a strong negative impact on animal welfare, productivity, and food safety. Furthermore, its smart pathogenesis, including facultative intracellular parasitism, increasingly serious antimicrobial resistance, and biofilm formation, make it challenging to be treated by conventional therapy. Therefore, the development of nanoparticles, especially liposomes, polymeric nanoparticles, solid lipid nanoparticles, nanogels, and inorganic nanoparticles, are gaining traction and excellent tools for overcoming the therapeutic difficulty accompanied by S. aureus mastitis. Therefore, in this review, the current progress and challenges of nanoparticles in enhancing the S. aureus mastitis therapy are focused stepwise. Firstly, the S. aureus treatment difficulties by the antimicrobial drugs are analyzed. Secondly, the advantages of nanoparticles in the treatment of S. aureus mastitis, including improving the penetration and accumulation of their payload drugs intracellular, decreasing the antimicrobial resistance, and preventing the biofilm formation, are also summarized. Thirdly, the progression of different types from the nanoparticles for controlling the S. aureus mastitis are provided. Finally, the difficulties that need to be solved, and future prospects of nanoparticles for S. aureus mastitis treatment are highlighted. This review will provide the readers with enough information about the challenges of the nanosystem to help them to design and fabricate more efficient nanoformulations against S. aureus infections.

Phosphatidylinositol-specific phospholipase C enhances epidermal penetration by Staphylococcus aureus

Staphylococcus aureus (S. aureus) commonly colonizes the human skin and nostrils. However, it is also associated with a wide variety of diseases. S. aureus is frequently isolated from the skin of patients with atopic dermatitis (AD), and is linked to increased disease severity. S. aureus impairs the skin barrier and triggers inflammation through the secretion of various virulence factors. S. aureus secretes phosphatidylinositol-specific phospholipase C (PI-PLC), which hydrolyses phosphatidylinositol and cleaves glycosylphosphatidylinositol-anchored proteins. However, the role of S. aureus PI-PLC in the pathogenesis of skin diseases, including AD, remains unclear. In this study, we sought to determine the role of S. aureus PI-PLC in the pathogenesis of skin diseases. PI-PLC was observed to enhance the invasion and persistence of S. aureus in keratinocytes. Besides, PI-PLC promoted the penetration of S. aureus through the epidermal barrier in a mouse model of AD and the human organotypic epidermal equivalent. Furthermore, the loss of PI-PLC attenuated epidermal hyperplasia and the infiltration of Gr-1⁺ cells and CD4⁺ cells induced by S. aureus infection in the mouse model of AD. Collectively, these results indicate that PI-PLC eases the entry of S. aureus into the dermis and aggravates acanthosis and immune cell infiltration in infected skin.

Molecular characteristics and antimicrobial susceptibility of Staphylococcus aureus among children with respiratory tract infections in southwest China

BACKGROUND

The molecular characteristics and antimicrobial susceptibility of Staphylococcus aureus (S. aureus) in general pediatric wards and county-level hospitals were rarely reported in China.

METHODS

Staphylococcus aureus was isolated from children hospitalized with respiratory tract infection (RTI) in Zhongjiang and Youyang counties in 2015. All isolates were typed by multilocus sequence, staphylococcal protein A, accessory gene regulator (agr), and staphylococcal cassette chromosome mec [SCCmec, for methicillin-resistant S. aureus (MRSA) only]. Polymerase chain reaction was used to screen 21 super-antigen (SAg) genes and panton-valentine leukocidin (pvl). Antimicrobial susceptibility testing was performed by E test.

RESULTS

A total of 2136 children were enrolled. Overall, 125 (5.9%) children carried S. aureus, among which MRSA accounted for 42.4%. ST59-SCCmec type IV-t437-agr group I (58.5%) was the most prevalent genotype in MRSA, and ST188-t189-agr group I (22.2%) was the top genotype in methicillin-sensitive S. aureus (MSSA). The pvl carriage rate in MRSA and MSSA was 15.1% and 9.7%, respectively (P = 0.4112). About 96.8% of S. aureus isolates were positive for at least one SAg gene. The most common SAg gene profile in the dominant ST59 clone was seb-sek-seq (42.8%). All S. aureus isolates were resistant to penicillin and erythromycin (minimum inhibitory concentration 90 was > 32 and 256 mg/L to penicillin and erythromycin, respectively), but usually susceptible to other tested non-β-lactam antimicrobials.

CONCLUSIONS

Staphylococcus aureus and MRSA were detected with a high frequency in children with RTI in county-level hospitals of China. ST59-SCCmec type IV-t437-agr group I was the dominant MRSA clone. The S. aureus isolates exhibited high resistance to penicillin and erythromycin.

The clinical significance of fungi in atopic dermatitis

Atopic dermatitis (AD) is one of the most common chronic inflammatory skin diseases and is caused by multiple factors including genetic factors, skin barrier defects, host immune responses, allergen sensitivity, environmental effects, and infections. Commonly, bacterial and viral infections are present in the eczematous lesions of AD patients and clearly aggravate the symptoms. However, studies of fungal infections in AD are limited in spite of the fact that there are reports showing that Malassezia, Candida, and some dermatophytes can affect the symptoms of AD. Moreover, certain fungal infections are sometimes overlooked and need to be considered particularly in AD patients with treatment failure as clinical features of those fungal infections could mimic eczematous lesions in AD. Here, we review the epidemiology, pathogenesis, clinical manifestations, and overlooked features of fungal infections associated with the symptoms of AD including the diagnosis and effectiveness of fungal treatments in AD patients.

Microbial interactions in the atopic march

The human body is populated by a large number of microorganisms and exist in symbiosis with these immensely diverse communities, which are suggested to influence health and disease. The microbiota plays an essential role in the maturation and function of the immune system. The prevalence of atopic diseases has increased drastically over the past decades, and the co-occurrence of multiple allergic diseases and allergic sensitization starting in early life has gained a great deal of attention. Immune responses in different organs affected by allergic diseases (e.g. skin, intestine and lung) may be linked to microbial changes in peripheral tissues. In the current review, we provide an overview of the current understanding of microbial interactions in allergic diseases and their potential role in the atopic march.

Microbe-host interplay in atopic dermatitis and psoriasis

Despite recent advances in understanding microbial diversity in skin homeostasis, the relevance of microbial dysbiosis in inflammatory disease is poorly understood. Here we perform a comparative analysis of skin microbial communities coupled to global patterns of cutaneous gene expression in patients with atopic dermatitis or psoriasis. The skin microbiota is analysed by 16S amplicon or whole genome sequencing and the skin transcriptome by microarrays, followed by integration of the data layers. We find that atopic dermatitis and psoriasis can be classified by distinct microbes, which differ from healthy volunteers microbiome composition. Atopic dermatitis is dominated by a single microbe (Staphylococcus aureus), and associated with a disease relevant host transcriptomic signature enriched for skin barrier function, tryptophan metabolism and immune activation. In contrast, psoriasis is characterized by co-occurring communities of microbes with weak associations with disease related gene expression. Our work provides a basis for biomarker discovery and targeted therapies in skin dysbiosis.

Atopic dermatitis (AD) and psoriasis (PSO) are associated with dysbiosis. Here, by analyses of skin microbiome and host transcriptome of AD and PSO patients, the authors find distinct microbial and disease-related gene transcriptomic signatures that differentiate both diseases.

Emollient formulations containing antiseptics reduce effectively the level of Staphylococcus aureus on skin

Background

Increased skin colonization by Staphylococcus aureus is associated with atopic eczema (AE) severity. Reduction of S. aureus levels on the skin results in an improvement in the clinical condition.

Methods

The antimicrobial activity of topical products including a bath oil, cream, and wash combining antiseptics and emollients (A+E) was compared to products containing emollients only. The preference of patients with AE for A+E cream or emollient only cream to relieve symptoms of itching, erythema, and inflammation when applied three times daily for 10 days is evaluated. Repeat insult patch testing of the products is also conducted.

Results

A significant reduction in microbial counts was found following use of A+E bath oil (4.09±0.32 vs 6.20±0.24 log₁₀ cfu/mL S. aureus, P<0.001), A+E cream (5.50±0.63 vs 5.94±0.72 log₁₀ cfu/foot S. aureus, P=0.002), and A+E wash (2.71±0.48 vs 3.57±0.31 log₁₀ cfu/mL Escherichia coli, P<0.001) compared to the emollient only products. The A+E cream was preferred to the emollient only cream (P=0.004) by patients with AE. All three tested formulations were found to be non-irritating and non-sensitizing to the skin.

Conclusion

The bath oil, cream, and wash containing antiseptics and emollients decrease the level of bacteria on the skin, including S. aureus, compared to emollient only products. Patients with AE preferred the A+E cream compared to the emollient only cream to relieve symptoms of itching, erythema, and inflammation. The choice of formulation allows clinicians and patients to choose a suitable product for the short-term treatment of eczema flare-ups caused by bacterial infections.

Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use:

https://www.youtube.com/watch?v=GqOXD7kHiSA

The role of Staphylococcus aureus in atopic dermatitis: microbiological and immunological implications

Introduction

Atopic dermatitis (AD) is an inflammatory disease characterised by chronic and recurrent course. Its predominant symptom is skin pruritus. Therefore, many AD patients have recurrent skin infections and are susceptible to the colonisation of apparently healthy skin and nasal vestibule by Staphylococcus aureus (S. aureus). Some S. aureus strains are capable of producing exotoxins.

Aim

To assess the relation between the total IgE (tIgE) and asIgE targeted against SEA (SEA-sIgE) and SEB (SEB-sIgE), as indicators of the severity of the course of AD, and the presence of S. aureus on apparently healthy skin, in skin lesions and in the nasal vestibule.

Material and methods

The research was performed in a population of 134 AD patients (61 men and 73 women) aged 2–86 years. Three smears were collected for microbiological investigations: from the nasal vestibule, from the skin where lesions appeared at the moment of investigations and from the skin which was free from the eczema. On collection the material was cultured on solid and broth mediums. After incubation each medium was thoroughly analysed for the presence of S. aureus.

Results

There was a statistically significant correlation between healthy skin colonisation by S. aureus and increased SEA-sIgE. The same correlation was proved between healthy skin colonisation by S. aureus and increased SEB-sIgE. There was a statistically significant correlation between colonisation of the nasal vestibule by S. aureus and the SEA-sIgE and SEB-sIgE serum concentration.

Conclusions

It seems that the colonisation of the lesioned skin, healthy skin and the anterior nares by S. aureus is related with higher tIgE serum concentration, which translates to more severe course of the disease. Significantly increased SEA-IgE and SEB-IgE concentrations were observed in the patients whose tIgE serum concentration was statistically higher.

Staphylococcus aureus from atopic dermatitis skin accumulates in the lysosomes of keratinocytes with induction of IL-1α secretion via TLR9

BACKGROUND

Staphylococcus aureus (S. aureus) is frequently detected in the skin of patients with atopic dermatitis (AD), and involved in the flare of AD. There are some evidence-specific strains of S. aureus affect the severity of AD. However, the mechanism of predominant colonization and the aggravation of dermatitis by certain strains of S. aureus in the patients with AD are still unknown.

OBJECTIVE

To reveal the characteristics of S. aureus from patients with AD (S. aureus-AD), we analyzed the interaction of S. aureus-AD and keratinocytes in comparison with those of S. aureus laboratory strains (S. aureus-stand.).

METHODS

We stimulated HaCaT cells, keratinocyte cell line, and human epidermal keratinocytes by heat-killed S. aureus strains, then evaluated immune response of keratinocytes by ELISA, immunofluorescence staining, and flow cytometry.

RESULTS

Upon incubation with keratinocytes, three out of four strains of heat-killed S. aureus-AD were strongly agglutinated inside the cytoplasm. In the cells, they are located in lysosomes and promoted the secretion of interleukin-1α (IL-1α). These reactions were not observed by any of four strains of S. aureus-stand. and S. epidermidis and were abolished by the treatment of S. aureus with proteinase K. Moreover, the IL-1α secretion was diminished by the inhibition of Toll-like receptor 9 (TLR9).

CONCLUSION

S. aureus-AD accumulates in lysosome of keratinocytes by means of bacterial cell wall proteins and induces IL-1α via TLR9.

Decolonization of Staphylococcus aureus in Healthcare: A Dermatology Perspective

The bacterium Staphylococcus aureus is responsible for significant morbidity, mortality, and financial burden in healthcare. It easily colonizes susceptible patients and can cause recurrent infections, especially in populations at risk. In addition to treating sequelae of infections, there is a growing body of literature aimed at decolonizing susceptible patients in order to prevent infection and also to prevent spread. Such strategies are widely employed in surgical, intensive care, and hospitalist fields. Staphylococcus aureus involvement has been implicated in the pathogenesis and persistence of many dermatologic diseases that are treated in the outpatient setting. This review serves to summarize current evidence for the management of Staphylococcus aureus colonized patients, as well as the evidence available for decolonization. We further characterize the role that colonization may play in atopic dermatitis, recurrent infections, hand eczema, cutaneous T-cell lymphoma, and also in surgical infections after Mohs surgery.

Water-based extracts of Zizania latifolia inhibit Staphylococcus aureus infection through the induction of human beta-defensin 2 expression in HaCaT cells

Zizania latifolia is a perennial herb belonging to the family Gramineae that has been used as a health food in Asian countries. In this study, we investigated the antimicrobial effect of Z. latifolia, which increased human beta-defensin 2 (hBD2) expression in HaCaT cells. hBD2 expression was further increased in cells treated with Z. latifolia extracts and subsequently infected with Staphylococcus aureus. Inversely, S. aureus infection decreased after treatment. The induction of hBD2 in HaCaT cells was mediated by the Toll-like receptor 2 (TLR2) signaling pathway, including the activation of extracellular signal-regulated kinase (ERK) and activator protein 1 (AP-1). Further study using siRNA revealed that hBD2 played an important role in the inhibition of S. aureus infection in HaCaT cells. Our data suggest that Z. latifolia extracts can be used as an antimicrobial ingredient for skin treatment formulas.

A Real-Life Based Evaluation of the Effectiveness of Antibacterial Fabrics in Treating Atopic Dermatitis

BACKGROUND

Antibacterial clothes are classified as a complementary treatment in line with antisepsis, although meta-studies are unable to find significant improvements of eczemas.

METHODS

The antibacterial effectiveness of conventional AD clothes was compared across each other by (i) standard suspension tests for the appraisal of antibacterial products and (ii) a real-life setup of affected AD skin using S. aureus colonised artificial skin, to assess if functional clothes are effective under practical wear conditions. Additionally, the interaction of the fibre types with a moisturising cream was evaluated during a real wearing situation and after domestic laundry.

RESULTS

In the real-life setup simulating dry skin microenvironment, all samples failed to reduce S. aureus. Silver and zinc-fabrics showed a slight activity only under unrealistic moist conditions. When using standard suspension tests, samples differed considerably in their antibacterial effectiveness, where silver and zinc endowed fibres outperformed AEGIS endowed silk fabrics. Garments absorbed the cream dependent on the particular fibre types. Furthermore, domestic laundry was unable to completely remove the cream.

CONCLUSION

Considerable differences in the antibacterial effectiveness of conventional AD clothes were revealed. Under practical (dry) wear conditions, garments were unable to modify skin colonization with S. aureus, although effectiveness can be triggered by wetting the garments. Remnants of moisturising cream remain on the fibres after laundry.

Atopic dermatitis: the skin barrier and beyond

BACKGROUND

Atopic dermatitis is the most common chronic inflammatory skin disorder, affecting up to 20% of children and 10% of adults in industrialized countries. This highly debilitating condition poses a considerable burden to both the individual and society at large. The pathophysiology of atopic dermatitis is complex, encompassing both genetic and environmental risk factors.

METHODS

This is a narrative review based on a systematic literature search.

CONCLUSIONS

Dysregulation of innate and adaptive immunity plays a key role; however, recent epidemiological, genetic and molecular research has focused interest on skin barrier dysfunction as a common precursor and pathological feature. Current understanding of the aetiology of atopic dermatitis highlights disruption of the epidermal barrier leading to increased permeability of the epidermis, pathological inflammation in the skin, and percutaneous sensitization to allergens. Thus, most novel treatment strategies seek to target specific aspects of the skin barrier or cutaneous inflammation. Several studies have also shown promise in preventing atopic dermatitis, such as the early use of emollients in high-risk infants. This may have broader implications in terms of halting the progression to atopic comorbidities including food allergy, hay fever and asthma.

Draft Genome Sequences of Five Methicillin-Sensitive Staphylococcus aureus Isolates from Skin Lesions in Patients with Atopic Dermatitis in the Russian Federation

We present here draft genome sequences of five Staphylococcus aureus strains obtained from children suffering from atopic dermatitis. The strains were determined to be of five different sequence types (sequence type 1 [ST1], ST7, ST8, ST15, and ST101) and carried a unique combination of superantigen-like protein (SSL) and serine protease genes.

Role of Superantigens in Allergic Inflammation: Their Relationship to Allergic Rhinitis, Chronic Rhinosinusitis, Asthma, and Atopic Dermatitis

OBJECTIVES

Our intention was to review all material published to date regarding superantigens (SAgs) and allergy from an otorhinolaryngological viewpoint to understand this association more clearly.

METHODS

We identified all materials published mentioning both SAg and allergic rhinitis (AR), chronic sinusitis, asthma, and atopic dermatitis (AD) that are indexed on PubMed, Google, or the ProQuest Central databases.

RESULTS

Staphylococcus aureus is a significant bacterial pathogen in humans and has the ability to produce enterotoxins with superantigenic features. The inflammatory response in allergy seen in both B cell and T cell may be attributed to SAgs. Sufferers of both allergic asthma with rhinitis and AR alone produce serological evidence of immunoglobulin E formation to SAgs produced by S. aureus. Perennial AR sufferers carry S. aureus more frequently and the presence of the organism within the nasal cavity may exacerbate perennial AR. SAg produced by S. aureus potentially worsens the asthmatic inflammatory response within the airway and may lead to the airways becoming hyperresponsive, as well as possibly activating T cells if asthmatic control is poor. Staphylococcal SAgs potentially increase the risk of developing chronic rhinosinusitis with nasal polyposis, additionally being a marker for more severe disease. If SAgs bring about chronic inflammatory responses in the nose and sinuses, then T cells excreting interferon-gamma may be a crucial mediator. In allergic dermatitis, S. aureus could be a key player in exacerbation of the condition. Even in younger pediatric patients with allergic dermatitis, allergic hypersensitivity to SAgs is frequent and may be a factor explaining how severe the condition becomes.

CONCLUSION

Just as SAgs are known to feature in many allergic conditions, they play their part in AR, chronic rhinosinusitis, asthma, and AD. Further research is required before the relationship between SAgs and allergy can be adequately explained.

The Role of Immune Defects and Colonization of Staphylococcus aureus in the Pathogenesis of Atopic Dermatitis

Atopic dermatitis (AD) is a condition with a complex and not fully understood etiology. In patients with AD, acute skin lesions are colonized by a greater number of Staphylococcus aureus (S. aureus) bacteria than chronic lesions, clinically unchanged atopic skin, or the skin of healthy people. Mechanisms promoting skin colonization by S. aureus include complex interactions among several factors. Apart from increased adhesion of S. aureus in atopic skin, defects of the innate immune response resulting in the lack of restriction of the growth of microorganisms also contribute to susceptibility to colonization by and infection with S. aureus. A deficiency in the endogenous antimicrobial peptides may be partly responsible for the susceptibility to colonization by and skin infection with S. aureus in patients with AD. Majority of isolated S. aureus stains are able to produce exotoxins, which act as superantigens. Moreover, anti-S. aureus-specific IgE was identified and measured in patients with AD, revealing that its level corresponds to the severity of the disease. This review of the literature attempts to identify factors that are involved in the pathogenesis of AD-related S. aureus skin colonization. In the light of presented mechanisms, a reduction of colonization may become both causative and symptomatic treatment in AD.

Immunologic, microbial, and epithelial interactions in atopic dermatitis

OBJECTIVE

To provide an overview of studies contributing to the understanding of immunologic, microbial, and epithelial interactions in atopic dermatitis.

DATA SOURCES

PubMed literature review (2000-2017) and meeting abstracts from recent international dermatology conferences.

STUDY SELECTIONS

Articles discussing primarily human disease.

RESULTS

Clinical studies showed that atopic dermatitis is a type 2 immune-centered disease with a systemic inflammatory component but with heterogeneous treatment responses. This suggests that other factors are likely involved in shaping the skin disease phenotype, including microbial dysbiosis and epidermal barrier dysfunction.

CONCLUSION

Recent clinical investigation has significantly expanded our knowledge on disease pathogenesis in atopic dermatitis, and current and future clinical trials will most likely further help to elucidate this complex, heterogeneous skin disease.

Infectious Complications in Atopic Dermatitis

Atopic dermatitis is characterized by the interplay of skin barrier defects with the immune system and skin microbiome that causes patients to be at risk for infectious complications. This article reviews the pathogenesis of atopic dermatitis and the mechanisms through which patients are at risk for infection from bacterial, viral, and fungal pathogens. Although these complications may be managed acutely, prevention of secondary infections depends on a multipronged approach in the maintenance of skin integrity, control of flares, and microbial pathogens.

Decolonization of Staphylococcus aureus in patients with atopic dermatitis: a reason for increasing resistance to antibiotics?

INTRODUCTION

Exacerbation of atopic dermatitis can be associated with bacterial infection. The skin of patients is colonized with Staphylococcus aureus in 90% of cases. An attempt has been made to demonstrate that eradication significantly reduces the severity of the disease. Studies indicate the efficacy of topical antibiotics, topical corticosteroids and calcineurin inhibitors. Due to increasing resistance to drugs and the defective antimicrobial peptide profile, decolonization is virtually impossible.

AIM

To determine the prevalence of S. aureus colonization among patients with atopic dermatitis and to assess antimicrobial susceptibility of isolated strains to antibiotics, especially fusidic acid and mupirocin.

MATERIAL AND METHODS

One hundred patients with atopic dermatitis and 50 healthy subjects were microbiologically assessed for the carriage of S. aureus. Antimicrobial susceptibility tests were performed using the broth-microdilution method for antibiotics: ampicillin, ciprofloxacin, daptomycin, erythromycin, fusidic acid, linezolid, lincomycin, mupirocin, tetracycline and vancomycin.

RESULTS

Staphylococcus aureus strains were isolated from the majority of our patients, either from the skin (71%) or the anterior nares (67%). In the present study, 10% of isolations represented methicillin-resistant S. aureus (MRSA). Antibiotics exhibited diverse activities against clinical isolates of S. aureus. Among those tested, the highest rates of resistance were shown for ampicillin - 58.5%, lincomycin - 37.5% and erythromycin - 31.0%. Enhanced resistance levels were expressed to mupirocin (17.5%) and fusidic acid (15.5%).

CONCLUSIONS

According to the increasing rate of resistance and quick recolonization after discontinuation of the treatment, chronic use of topical antibiotics is not recommended and should be limited to exacerbation of atopic dermatitis with clinical signs of bacterial infection.

Role of Microbial Modulation in Management of Atopic Dermatitis in Children

The pathophysiology of atopic dermatitis (AD) is multifactorial and is a complex interrelationship between skin barrier, genetic predisposition, immunologic development, skin microbiome, environmental, nutritional, pharmacological, and psychological factors. Several microbial modulations of the intestinal microbiome with pre- and/or probiotics have been used in AD management, with different clinical out-come (both positive, as well as null findings). This review provides an overview of the clinical evidence from trials in children from 2008 to 2017, aiming to evaluate the effect of dietary interventions with pre- and/or pro-biotics for the treatment of AD. By searching the PUBMED/MEDLINE, EMBADE, and COCHRANE databases 14 clinical studies were selected and included within this review. Data extraction was independently conducted by two authors. The primary outcome was an improvement in the clinical score of AD severity. Changes of serum immunological markers and/or gastrointestinal symptoms were explored if available. In these studies some dietary interventions with pre- and/or pro-biotics were beneficial compared to control diets in the management of AD in children, next to treatment with emollients, and/or local corticosteroids. However, heterogeneity between studies was high, making it clear that focused clinical randomized controlled trials are needed to understand the potential role and underlying mechanism of dietary interventions in children with AD.

Clumping Factor B Promotes Adherence of Staphylococcus aureus to Corneocytes in Atopic Dermatitis

Staphylococcus aureus skin infection is a frequent and recurrent problem in children with the common inflammatory skin disease atopic dermatitis (AD). S. aureus colonizes the skin of the majority of children with AD and exacerbates the disease. The first step during colonization and infection is bacterial adhesion to the cornified envelope of corneocytes in the outer layer, the stratum corneum. Corneocytes from AD skin are structurally different from corneocytes from normal healthy skin. The objective of this study was to identify bacterial proteins that promote the adherence of S. aureus to AD corneocytes. S. aureus strains from clonal complexes 1 and 8 were more frequently isolated from infected AD skin than from the nasal cavity of healthy children. AD strains had increased ClfB ligand binding activity compared to normal nasal carriage strains. Adherence of single S. aureus bacteria to corneocytes from AD patients ex vivo was studied using atomic force microscopy. Bacteria expressing ClfB recognized ligands distributed over the entire corneocyte surface. The ability of an isogenic ClfB-deficient mutant to adhere to AD corneocytes compared to that of its parent clonal complex 1 clinical strain was greatly reduced. ClfB from clonal complex 1 strains had a slightly higher binding affinity for its ligand than ClfB from strains from other clonal complexes. Our results provide new insights into the first step in the establishment of S. aureus colonization in AD patients. ClfB is a key adhesion molecule for the interaction of S. aureus with AD corneocytes and represents a target for intervention.

Adjunctive Management of Itch in Atopic Dermatitis

Itch, or pruritus, is a hallmark feature of atopic dermatitis (AD). The impact of AD-related pruritus can range from mildly distressing or distracting to completely disabling. Traditionally, management of itch in AD patients has focused on restoring the altered skin barrier with topical emollients and/or reducing inflammation. A growing emphasis has been placed on directly targeting the neural transmission pathways that mediate itch signaling. Off-label use of neuromodulatory agents has helped reduce this aggravating symptom in atopic patients. This article reviews the current literature on the use of neuromodulatory agents and nonpharmacologic alternative therapies used to treat AD-related pruritus.

Expression of IL-22 in the Skin Causes Th2-Biased Immunity, Epidermal Barrier Dysfunction, and Pruritus via Stimulating Epithelial Th2 Cytokines and the GRP Pathway

Increased expression of Th22 cytokine IL-22 is a characteristic finding in atopic dermatitis (AD). However, the specific role of IL-22 in the pathogenesis of AD in vivo has yet to be elucidated. Consistent with observations in human AD, IL-22 was significantly increased in the AD skin of mice after epicutaneous sensitization to house dust mite allergen. Utilizing a skin-specific inducible transgenic system, we show in the present study that expression of IL-22 in the skin of mice caused an AD-like phenotype characterized by chronic pruritic dermatitis associated with Th2-biased local and systemic immune responses, downregulation of epidermal differentiation complex genes, and enhanced dermatitis upon epicutaneous allergen exposure. IL-22 potently induced the expression of gastrin-releasing peptide (GRP), a neuropeptide pruritogen, in dermal immune cells and sensory afferents and in their skin-innervating sensory neurons. IL-22 also differentially upregulated the expression of GRP receptor (GRPR) on keratinocytes of AD skin. The number of GRP+ cells in the skin correlated with the AD severity and the intensity of pruritus. IL-22 directly upregulated the expression of epithelial-derived type 2 cytokines (thymic stromal lymphopoietin and IL-33) and GRP in primary keratinocytes. Furthermore, GRP not only strongly induced thymic stromal lymphopoietin but it also increased the expression of IL-33 and GRPR synergistically with IL-22. Importantly, we found that the expression of GRP was strikingly increased in the skin of patients with AD. These results indicate that IL-22 plays important pathogenic roles in the initiation and development of AD, in part through inducing keratinocyte production of type 2 cytokines and activation of the GRP/GRPR pathway.

Atopic Eczema: Genetic Associations and Potential Links to Developmental Exposures

Atopic eczema (AE), or atopic dermatitis (AD), is a common inflammatory skin disease with a disrupted epidermal barrier and an allergic immune response. AD/AE is prominently characterized by a symptomatic itch and transient skin lesions. Infants compose a significant percentage affected. Two models have been proposed to explain AD/AE skin pathology: the gut microbiome-focused inside-outside model and the outside-inside model concentrating on the disrupted skin barrier/skin microbiome. Gene disruptions contributing to epidermal structure, as well as those in immune system genes, are implicated. Over 30 genes have been linked to AD/AE with Flg and Tmem79/Matt alterations being common. Other linked disruptions are in the interleukin-1 family of cytokines/receptors and the TH2 gene family of cytokines. Inheritable epigenetic modifications of the genes or associated proteins may also be involved. Skin barrier disruption and the allergic immune response have been the main foci in mechanistic studies of AD/AE, but the role of the environment is becoming more apparent. Thus, an examination of in utero exposures could be very helpful in understanding the heterogeneity of AD/AE. Although research is limited, there is evidence that developmental exposure to environmental tobacco smoke or phthalates may impact disease. Management for AD/AE includes topical corticosteroids and calcineurin inhibitors, which safely facilitate improvements in select individuals. Disease heterogeneity warrants continued research not only into elucidating disease mechanism(s), via identification of contributing genetic alterations, but also research to understand how/when these genetic alterations occur. This may lead to the cure that those affected by AD/AE eagerly await.

Staphylococcus aureus Induces Increased Serine Protease Activity in Keratinocytes

Bacteria that reside on the skin can influence the behavior of the cutaneous immune system, but the mechanisms responsible for these effects are incompletely understood. Colonization of the skin by Staphylococcus aureus (S. aureus) is increased in atopic dermatitis and can result in increased severity of the disease. In this study, we show that S. aureus stimulates human keratinocytes to increase their endogenous protease activity, including specific increases in trypsin activity. This increased protease activity coincided with increased expression of mRNA for kallikreins (KLKs), with KLK6, 13, and 14 showing the greatest induction after exposure to S. aureus. Suppression of mRNA for these KLKs in keratinocytes by targeted small interfering RNA silencing before S. aureus exposure blocked the increase in protease activity. Keratinocytes exposed to S. aureus showed enhanced degradation of desmoglein-1 and filaggrin, whereas small interfering RNA for KLK6, KLK13, and KLK14 partially blocked this degradation. These data illustrate how S. aureus directly influences the skin barrier integrity by stimulating endogenous proteolytic activity and defines a previously unknown mechanism by which S. aureus may influence skin diseases.

Effects of Emollient Containing Bee Venom on Atopic Dermatitis: A Double-Blinded, Randomized, Base-Controlled, Multicenter Study of 136 Patients

BACKGROUND

Atopic dermatitis (AD) is a common, complex disease that follows a chronic relapsing course and significantly affects the quality of life of patients. Skin barrier dysfunction and inflammatory processes induce and aggravate this skin condition. Proper use of an emollient for hydration is a keystone of AD treatment. Bee venom is known to have anti-inflammatory effects and has been widely used in traditional medicine to treat various inflammatory disorders.

OBJECTIVE

To find out the beneficial effect of an emollient containing bee venom in the treatment of patients with AD.

METHODS

This study included 136 patients with AD who were randomized to receive either an emollient containing bee venom and silk-protein or a vehicle that was identical except for the bee venom for 4 weeks. The patients were instructed to apply the emollient twice daily on their entire body and not to use other medications, including topicals, during the course of the study. The eczema area and severity index (EASI) score, transepidermal water loss, and visual analogue scale (VAS) score of itching were evaluated at the first visit and after 2 and 4 weeks. The investigator global assessment was evaluated at 2 and 4 weeks after the application of emollient containing bee venom or vehicle.

RESULTS

Patients applying emollient containing bee venom showed significantly lower EASI score and VAS value compared to patients applying emollient without bee venom.

CONCLUSION

Emollient containing bee venom is a safe and effective option for patients with AD.

Effects of a New Emollient-Based Treatment on Skin Microflora Balance and Barrier Function in Children with Mild Atopic Dermatitis

BACKGROUND/OBJECTIVES

The use of emollients is widely recommended for the management of atopic dermatitis (AD), especially between flares. An imbalance of skin microflora is suspected of playing a key role in exacerbations of AD. Our aim was to evaluate the effect of a new emollient balm on clinical parameters (SCORing Atopic Dermatitis [SCORAD], xerosis, pruritus), skin barrier function (transepidermal water loss and loricrin, filaggrin, corneodesmosin, and involucrin expression], skin microflora biodiversity, and Staphylococcus aureus and Staphylococcus epidermidis balance in children with mild AD.

METHODS

Fifty-four children (1-4 yrs old) were enrolled in this randomized, controlled study. Subjects applied a hygiene product and the emollient balm (emollient group, n = 28) or the hygiene product only (control group, n = 26) twice a day for 28 days.

RESULTS

We found improvement in favor of the emollient group in SCORAD (p < 0.001), pruritus (p = 0.06), and xerosis (p = 0.06) after 28 days of application. Moreover, transepidermal water loss decreased in the emollient group by 34% (p = 0.06) and involucrin expression by 37% (p = 0.001) at day 28 from baseline in association with improvement in barrier function, whereas other barrier-specific proteins did not vary. S. aureus increased significantly in the control group only (6.5 times, p = 0.01), whereas S. epidermidis remained stable in both groups. The Shannon index (H' = 2.3) did not vary with treatment in either group.

CONCLUSION

Twice-daily application of a new emollient balm in children with mild AD protected the skin from S. aureus proliferation and preserved microflora biodiversity.

The role of the skin microbiome in atopic dermatitis

Atopic dermatitis (AD) is a common skin disease that affects a large proportion of the population worldwide. The incidence of AD has increased over the last several decades along with AD's burden on the physical and psychological health of the patient and family. However, current advances in understanding the mechanisms behind the pathophysiology of AD are leading to a hopeful outlook for the future. Staphylococcus aureus (S. aureus) colonization on AD skin has been directly correlated to disease severity but the functions of other members of the skin bacterial community may be equally important. Applying knowledge gained from understanding the role of the skin microbiome in maintaining normal skin immune function, and addressing the detrimental consequences of microbial dysbiosis in driving inflammation, is a promising direction for development of new treatments. This review discusses current preclinical and clinical research focused on determining how the skin microbiome may influence the development of AD.

Turning the inside out: the microbiology of atopic dermatitis

Allergy is on the rise worldwide. The hygiene hypothesis of atopic diseases linked microbes with atopic dermatitis (AD) both as drivers and modulators of skin pathology. The earlier literature favoured an inside-outside model of AD where an immunological abnormality compounded by a gut microbiota dysbiosis is the primary event. Probiotic intervention trials with lactobacilli and bifidobacteria as well as the application of bifidogenic oligosaccharide prebiotics showed indeed promising clinical results, but no consistent gut microbiota dysbiosis could be linked with AD. An alternative hypothesis known as outside-inside model of AD considers a genetic skin barrier effect compounded by a skin microbiota dysbiosis as primary pathogenic event. Cultivation microbiology has demonstrated strong skin colonization with superantigen-encoding Staphylococcus aureus in AD patients; microbiota and molecular microbiome analyses demonstrated that S. aureus abundance fluctuates and parallels clinical symptoms. In a mouse model, δ-toxin of S. aureus induced mast cell degranulation, leading to AD-like symptoms. Mutant mice developing AD symptoms showed increased skin colonization with S. aureus; antibiotic treatment alleviated the symptoms. Clinical trials showed that various treatments reducing S. aureus skin load also reduced AD symptoms, suggesting S. aureus as a potential critical driver of AD and a target for antimicrobial interventions other than antibiotics.

Effects of the Staphylococcus aureus and Staphylococcus epidermidis Secretomes Isolated from the Skin Microbiota of Atopic Children on CD4+ T Cell Activation

Interactions between the immune system and skin bacteria are of major importance in the pathophysiology of atopic dermatitis (AD), yet our understanding of them is limited. From a cohort of very young AD children (1 to 3 years old), sensitized to Dermatophagoides pteronyssinus allergens (Der p), we conducted culturomic analysis of skin microbiota, cutaneous transcript profiling and quantification of anti-Der p CD4+ T cells. This showed that the presence of S. aureus in inflamed skin of AD patients was associated with a high IgE response, increased expression of inflammatory and Th2/Th22 transcripts and the prevalence of a peripheral Th2 anti-Der p response. Monocyte-derived dendritic cells (moDC) exposed to the S. aureus and S. epidermidis secretomes were found to release pro-inflammatory IFN-γ and anti-inflammatory IL-10, respectively. Allogeneic moDC exposed to the S. aureus secretome also induced the proliferation of CD4+ T cells and this effect was counteracted by concurrent exposure to the S. epidermidis secretome. In addition, whereas the S. epidermidis secretome promoted the activity of regulatory T cells (Treg) in suppressing the proliferation of conventional CD4+ T cells, the Treg lost this ability in the presence of the S. aureus secretome. We therefore conclude that S. aureus may cause and promote inflammation in the skin of AD children through concomitant Th2 activation and the silencing of resident Treg cells. Commensals such as S. epidermidis may counteract these effects by inducing the release of IL-10 by skin dendritic cells.

CCL17 production by mouse langerhans cells stimulated with Staphylococcus aureus cell wall components

Patients with atopic dermatitis (AD) show increased numbers of Th2 cells in their acute skin lesions and superficial skin colonization by Staphylococcus aureus. The purpose of this study was to clarify the effect of S. aureus cell wall components on Th2 chemokine production by murine Langerhans cells (LCs). Murine LCs were stimulated with peptidoglycan (PEG) and/or muramyldipeptide (MDP) for 24 or 48 h, and Th1 and Th2 chemokine production was investigated by reverse transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). PEG-stimulation of LCs induced production of the Th2 chemokine CCL17 and this was enhanced in the presence of interleukin (IL)-4. A low-molecular weight PEG fragment, MDP, did not induce CCL17 production by LCs. However, when LCs were stimulated with PEG in combination with MDP, PEG-induced CCL17 production was synergistically enhanced by MDP. Furthermore, PEG- and MDP-induced CCL17 production was enhanced to a greater extent in the presence of IL-4. These results suggest that S. aureus colonization in AD patients may enhance the Th2-prone immune response through upregulation of CCL17 production by LCs, which would occur as a result of simultaneous stimulation with PEG and MDP from S. aureus in a Th2 environment.