Application of lipidomics to reveal differences of facial skin surface lipids between atopic dermatitis and healthy infants

Current Insights on Lipidomics in Dermatology: A Systematic Review

Inflammatory dermatoses and lipid disturbances are interrelated, especially owing to chronic inflammatory conditions. This study aimed to investigate recent findings about lipidomic and dermatologic diseases as well as on the sampling techniques developed to study lipidomics in vivo and analytical and statistical approaches employed. A systematic review was designed using the search algorithm (lipidomics) AND (skin OR dermatology OR stratum corneum OR sebum OR epidermis), following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The literature search identified 1013 references, and finally, only 48 were selected, including a total of 2651 participants with a mean age of 34.13 ± 16.28 years. The dermatologic diseases evaluated were atopic dermatitis, acne, psoriasis, hidradenitis suppurativa, and other skin diseases. Sebutape was the primary sampling technique for lipidomics research. Most of the studies performed untargeted profiling through liquid chromatography with tandem mass spectrometry statistically analyzed with principal component analysis, orthogonal partial least-squares discriminate analysis, heatmap, and volcano plot models. The most consulted databases were LIPIDMAPS Structure Database, MetaboAnalyst, and Human Metabolome Database. A large heterogeneity of lipidomic and lipid metabolism profiles was observed in patients with skin diseases. Skin lipidomic analysis is valuable in exploring skin disease and has ample translational potential.

Correlation study of facial lipid profile differences and skin physiological characteristics in Chinese women aged 19-33 years

BACKGROUND

Changes in the stratum corneum (SC) lipid profiles are associated with various skin diseases. Factors, including age, ethnicity, season and anatomical location, can influence the variations in SC lipid profiles. According to reports, the facial sebum of Chinese women peaks at age 20-30, accompanied by various signs of facial ageing. No studies have investigated how facial SC lipid profiles change with age in young Chinese women.

OBJECTIVES

This study aimed to observe the differences in the facial SC lipid profiles of Chinese female volunteers aged 19-33 and determined the relationship between key lipids and physiological parameters.

METHODS

Differential lipids were detected and screened in healthy Chinese women aged 19-33 through ultra-performance liquid chromatography-mass spectrometry. The relationship between these lipids and the skin's physiological parameters was determined.

RESULTS

The facial SC lipid profiles of young Chinese women exhibited significant differences with age. The results indicated that 40 lipids increased with age, while 51 types decreased. The average chain length of diglycerides (DG), triglycerides (TG) and short-chain ceramides decreased with age, while cholesterol esters (CE) and ceramides {Cer, Cer/EODS (d19:0/18:1/O/16:0) and Cer/EOS (d28:1/12:0/O/14:0)} increased with age. Cer/EODS (d19:0/18:1/O/16:0), Cer/EOS (d28:1/12:0/O/14:0) and HexCer/NDS (d14:0/33:1) were positively correlated with trans-epidermal water loss, skin elasticity and skin brightness, while Cer/AP (t18:0/20:0) was negatively correlated with skin elasticity. This study comprehensively explains the differences in lipid profile composition and skin ageing in young populations.

CONCLUSIONS

Young Chinese women's facial skin SC lipid profiles significantly change with age. Age-related changes result in variations in DG and CE levels and changes in the chain lengths of TG and Cer. Age-related changes in Cer content affect skin barrier function, elasticity and brightness.

Circadian Rhythms of Skin Surface Lipids and Physiological Parameters in Healthy Chinese Women Reveals Circadian Changes in Skin Barrier Function

BACKGROUND

Circadian rhythms are driven by the biological clock, an endogenous oscillator that generates approximately 24 h cycles in mammals. The circadian regulation of the lipid metabolism plays a crucial role in overall metabolic health. An analysis of the correlation between the skin's physiological parameters and skin lipids can provide a better insight into the rhythmic changes in skin condition.

OBJECTIVES

The aim was to reveal how skin surface lipids (SSLs) participate in the regulation of circadian rhythms in the skin and the importance of the circadian oscillation of facial lipid molecules in maintaining epidermal homeostasis.

METHODS

Changes in SSLs were assessed using UPLC-QTOF-MS. The skin's physiological parameters were quantified using non-invasive instruments. Multivariate data analysis was employed to evaluate the differences.

RESULTS

Both skin surface lipids and physiological parameters exhibited certain circadian variation patterns. Four major lipid classes (fatty acids, glycerophospholipids, prenol lipids, saccharolipids) exhibited circadian rhythmic trends, with seven lipid subclasses contributing most significantly to the overall patterns observed. Among the physiological parameters assessed, sebum secretion, transepidermal water loss, moisture measurement value, and skin surface temperature exhibited sinusoidal circadian rhythms. Further analysis revealed significant correlations between fatty acids and saccharolipids with moisture measurement values, and between glycerolipids and pH value. In addition, lipids closely associated with the barrier such as unsaturated fatty acids and ceramide chain lengths correlated significantly with moisture measurement values.

CONCLUSIONS

Through correlation analysis, the study elucidates the influence of diurnal fluctuations in skin surface lipids on skin barrier function. These findings hold significant implications for understanding skin barrier impairment associated with circadian rhythm disruptions.

Comparative study of melasma in patients before and after treatment based on lipomics

BACKGROUND

Skin barrier alterations play a crucial function in melasma development. Past researches have demonstrated variations in lipid content between the epidermis of melasma lesions and normal tissues, along with the varied expression of lipid-related genes in melasma. This study aimed to analyze the lipidome profiles of skin surface lipids (SSL) in patients with melasma before and after treatment to understand associated abnormalities.

METHODS

Melasma was treated with tranexamic acid orally and hydroquinone cream topically. Disease was assessed using the Melasma Area and Severity Index (MASI), and the impact to life was evaluated with Melasma Quality of Life (MELASQoL) score. Epidermal melanin particles were observed using reflection confocal microscopy (RCM), whereas epidermal pigment and blood vessel morphology were observed using dermoscopy, and SSL samples were collected. Specific information regarding alterations in lipid composition was obtained through multivariate analysis of the liquid chromatography-mass spectrometry data.

RESULTS

After treatment, patients with melasma exhibited decreased MASI and MELASQoL scores (P < 0.001); RCM revealed reduced melanin content in the lesions, and dermoscopy revealed fewer blood vessels. Fifteen lipid subclasses and 382 lipid molecules were identified using lipidomic assays. The expression levels of total lipids, phosphatidylcholine, and phosphatidylethanolamine in the melasma lesions decreased after treatment (P < 0.05).

CONCLUSION

This study revealed alterations in the SSL composition after effective melasma treatment, suggesting a compensatory role for lipids in melasma barrier function. The mechanism involving SSL and the lipid barrier, which influences melasma's occurrence, needs further elucidation.

Lipidomics and Metabolomics in Infant Atopic Dermatitis: What's the Correlation with Early Nutrition?

To date, the complex picture of atopic dermatitis (AD) has not yet been fully clarified, despite the important prevalence of this disease in the pediatric population (20%) and the possibility of persistence into adulthood, with important implications for the quality of life of those affected, as well as significant social and financial costs. The most recent scientific evidence suggests a new interpretation of AD, highlighting the important role of the environment, particularly that of nutrition in the early stages of development. In fact, the new indications seem to point out the harmful effect of elimination diets, except in rare cases, the uselessness of chrono-insertions during complementary feeding and some benefits, albeit weak, of breastfeeding in those at greater risk. In this context, metabolomics and lipidomics can be necessary for a more in-depth knowledge of the complex metabolic network underlying this pathology. In fact, an alteration of the metabolic contents in children with AD has been highlighted, especially in correlation to the intestinal microbiota. While preliminary lipidomic studies showed the usefulness of a more in-depth knowledge of the alterations of the skin barrier to improve the development of baby skin care products. Therefore, investigating the response of different allergic phenotypes could be useful for better patient management and understanding, thus providing an early intervention on dysbiosis necessary to regulate the immune response from the earliest stages of development.

A miniaturized comprehensive approach for total lipidome analysis and vitamin D metabolite quantification in human serum

The balance between the different lipid molecules present in biological fluids accurately reflects the health state of the organism and can be used by medical personnel to finely tune therapy to a single patient, a process known as precision medicine. In this work, we developed a miniaturized workflow for the analysis of different lipid classes at the intact level, as well as their fatty acid constituents, starting from human serum. Fatty acids were identified by using flow-modulated comprehensive gas chromatography coupled to mass spectrometry (FM-GC × GC-MS), and their relative amount as well as the ratio of specific FA classes was determined by using FM-GC × GC with a flame ionization detector. Ultra-high-performance liquid chromatography coupled to tandem mass spectrometry was used for the simultaneous quantification of vitamin D metabolites and assessment of different intact lipid classes. An MRM method was developed for the quantification of five vitamin D metabolites (vitamin D2, vitamin D3, 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, 24R,25-dihydroxyvitamin D3), and validated in terms of LoD, LoQ, accuracy, and precision, also using a certified reference material. At the same time, a combination of SCAN, precursor ion scan, and neutral loss scan, in both positive and negative modes, was used for the identification of 81 intact lipid species, such as phospholipids, cholesteryl esters, and triacylglycerols, in less than 25 min. In order to easily monitor the lipid composition and speed up the identification process, a two-dimensional map of the lipidome was generated, by plotting the molecular weight of the identified molecules versus their retention time. Moreover, a relative quantification was performed within each lipid class identified. The combination of untargeted and targeted data could provide useful information about the pathophysiological condition of the organism and evaluate, in a tailored manner, an efficient action.

Progress of metabolomics in atopic dermatitis: a systematic review

Atopic dermatitis (AD), a chronic inflammatory skin disorder characterized by recurrent eczema and intense pruritus, is a major skin-related burden worldwide. The diagnosis and treatment of AD is often challenging due to the high heterogeneity of AD, and its exact etiology is unknown. Metabolomics offers the opportunity to follow continuous physiological and pathological changes in individuals, which allows accurate diagnosis and management as well as providing deep insights into the etiopathogenesis of AD. Several metabolomic studies of AD have been published over the past few years. The aim of this review is to summarize these findings and help researchers to understand the rapid development of metabolomics for AD. A comprehensive and systematic search was performed using the PubMed, Embase, Cochrane Library and Web of Science databases. Twenty-six papers were finally included in the review after quality assessment. Significant differences in metabolite profiles were found between patients with AD and healthy individuals. This study provides a comprehensive overview of metabolomic research in AD. A better understanding of the metabolomics of AD may offer novel diagnostic, prognostic, and therapeutic approaches.

An Overview of the Latest Metabolomics Studies on Atopic Eczema with New Directions for Study

Atopic eczema (AE) is an inflammatory skin disorder affecting approximately 20% of children worldwide and early onset can lead to asthma and allergies. Currently, the mechanisms of the disease are not fully understood. Metabolomics, the analysis of small molecules in the skin produced by the host and microbes, opens a window to observe the mechanisms of the disease which then may lead to new drug targets for AE treatment. Here, we review the latest advances in AE metabolomics, highlighting both the lipid and non-lipid molecules, along with reviewing the metabolites currently known to reside in the skin.

Lipidomic analysis reveals altered lipid profiles of gingival tissues with periodontitis

AIM

The role of lipids in periodontitis has not been well studied. Thus, this study aimed to explore periodontitis-associated lipid profile changes and identify differentially expressed lipid metabolites in gingival tissues.

MATERIALS AND METHODS

Gingival tissues from 38 patients with periodontitis (periodontitis group) and 38 periodontally healthy individuals (control group) were collected. A UHPLC-QTOF-MS-based non-targeted metabolomics platform was used to identify and compare the lipid profiles of the two groups. The distribution and expression of related proteins were subsequently analyzed via immunohistochemistry to further validate the identified lipids.

RESULTS

Lipid profiles significantly differed between the two groups, and 20 differentially expressed lipid species were identified. Lysophosphatidylcholines (lysoPCs), diacylglycerols (DGs), and phosphatidylethanolamines (PEs) were significantly upregulated, while triacylglycerols (TGs) were downregulated in the periodontitis group. Moreover, the staining intensity of ABHD5/CGI-58, secretory phospholipase A2 (sPLA2), and sPLA2-IIA was significantly stronger in the gingival tissues of patients with periodontitis than in those of healthy controls.

CONCLUSIONS

LysoPCs, DGs, and PEs were significantly upregulated, whereas TGs were downregulated in gingival tissues of patients with periodontitis. Correspondingly, the immunohistochemical staining of ABHD5/CGI-58, sPLA2, and sPLA2-IIA in gingival tissues was consistent with the downstream production of lipid classes (lysoPCs, TGs, and DGs).

Classifying atopic dermatitis: a systematic review of phenotypes and associated characteristics

Atopic dermatitis is a heterogeneous disease, accompanied by a wide variation in disease presentation and the potential to identify many phenotypes that may be relevant for prognosis and treatment. We aimed to systematically review previously reported phenotypes of atopic dermatitis and any characteristics associated with them. Ovid EMBASE, Ovid MEDLINE and Web of Science were searched from inception till the 12th of February 2021 for studies attempting to classify atopic dermatitis. Primary outcomes are atopic dermatitis phenotypes and characteristics associated with them in subsequent analyses. A secondary outcome is the methodological approach used to derive them. In total, 8,511 records were found. By focusing only on certain clinical phenotypes, 186 studies were eligible for inclusion. The majority of studies were hospital-based (59%, 109/186) and cross-sectional (76%, 141/186). The number of included patients ranged from seven to 526,808. Data-driven approaches to identify phenotypes were only used in a minority of studies (7%, 13/186). Ninety-one studies (49%) investigated a phenotype based on disease severity. A phenotype based on disease trajectory, morphology and eczema herpeticum was investigated in 56 (30%), 22 (12%) and 11 (6%) studies, respectively. Thirty-six studies (19%) investigated morphological characteristics in other phenotypes. Investigated associated characteristics differed between studies. In conclusion, we present an overview of phenotype definitions used in literature for severity, trajectory, morphology and eczema herpeticum, including associated characteristics. There is a lack of uniform and consistent use of atopic dermatitis phenotypes across studies.

Optimal application method of a moisturizer on the basis of skin physiological functions

BACKGROUND

Clinical studies have clarified the usefulness of moisturizers for dry skin diseases. However, few reports exist on the appropriate application of moisturizers with respect to the skin physiological functions.

AIMS

To clarify the optimal moisturizer application method on the basis of skin physiological functions.

METHODS

This study investigated the appropriate time, dose, and frequency of moisturizer application from the perspective of skin physiology. In healthy subjects, the stratum corneum water content (SCW) was compared between different moisturizer application times (immediately [≤5 min] and 90 min after bathing), doses (0.5, 1.0, and 2.0 mg/cm² ), and frequencies (once and twice daily). Thereafter, patients with dry skin were treated with the moisturizer once or twice daily for 8 weeks at the time, and application dose was determined to be optimal for the healthy subjects; the moisturizing effect was evaluated based on the SCW, trypsin activity, and desmoglein 1 localization score in the stratum corneum.

RESULTS

In healthy subjects, compared to at control sites, the SCW was significantly higher at sites treated with the moisturizer immediately after bathing, with 1.0 and 2.0 mg/cm² of the moisturizer, and with once- and twice-daily applications. In patients with dry skin, the SCW was significantly higher compared to control sites and the desmoglein 1 localization score was significantly lower after 8 weeks only when the moisturizer was applied twice daily.

CONCLUSIONS

Moisturizer application of ≥1.0 mg/cm² twice daily (immediately after bathing at night and in the morning) had a moisturizing effect, as verified from the skin physiological functions.

Revealing the Correlation between Altered Skin Lipids Composition and Skin Disorders

Human skin layers serve as a barrier between the body and the environment, by preventing water loss and blocking the entry of chemicals, allergens, and microbes. Recent data showed that skin lipids are vital ‘key players’ of several functions and mechanisms performing in the skin, such as, barrier function and microbiome composition. Abnormalities in lipid composition have been observed in inflammatory cutaneous diseases with a disrupted skin barrier. This review aims to demonstrate the fundamental role of keratinocytes, sebocytes, and microbiome-derived lipids in the maintenance of the skin barrier. Furthermore, it would reveal the correlation between altered skin lipids’ composition, microbiome, and the occurrence of certain dermatological disorders such as acne vulgaris, atopic dermatitis, psoriasis, and rosacea.

Lipidomic analysis of facial skin surface lipid reveals the causes of pregnancy-related skin barrier weakness

Self-reported skin discomfort is a common problem during pregnancy, but it is not clear whether skin barrier function is altered in the process. Few studies have described the skin barrier function during pregnancy. In this work, we used highly sensitive and high-resolution ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) to distinguish skin surface lipid (SSL) combined with multivariate analysis of lipids and metabolic changes to determine the relationship between SSL changes and skin physiology during pregnancy in order to better understand the skin condition of pregnant women. The results showed a significant reduction in the total lipid content in pregnant women. A total of 2270 lipids were detected, and the relative abundances of fatty acyls and glycerolipids were significantly reduced, while glycerophospholipids (GPs), sphingolipids, and saccharolipids was significantly increased in the pregnancy group. Multivariate data analysis indicated that 23 entities constituted the most important individual species responsible for the discrimination and phosphatidylcholine was the most abundant lipid in pregnancy group. In addition, compared to SSL profile of control group, it was observed that the average chain length of ceramides and fatty acids both decreased in SSL profile of pregnancy group. The main and most commonly affected pathway was that of GP pathways. These findings indicate that skin lipids are significantly altered in mid-pregnancy compared to the control group. Changes in ostrogen during pregnancy also make the skin more susceptible to inflammatory factors and lead to more fragile and susceptible skin, weakening the skin barrier along with the lipid alterations.