Sweaty skin, background and assessments

Identification of a higher C-S lyase activity of Staphylococcus hominis in volunteers with unpleasant axillary odour

OBJECTIVE

Excessive and unpleasant odours that emanate from the skin can induce bromhidrosis and substantially impair a person's quality of life. Enzymatic pathways generating unpleasant odours are well detailed, and among them, the C-S lyase is one of the enzymes involved in the conversion of non-volatile precursors into thiol-type malodorous volatile molecules such as 3M3SH. This study aimed to investigate the variation of axillary odour intensity correlated with Staphylococcus (S.) hominis C-S lyase activity within a group of volunteers after a physical activity.

METHODS

First, a group of 24 volunteers from the same ethnicity with standardized hygienic and alimentary practices participated in a supervised indoor cycling activity. Following this session, worn T-shirts were recovered to enable the olfactory evaluation of axillary odours by qualified experts. To go further, the microbiota from the axillary zone of each volunteer was sampled and the bacterial relative abundance was investigated by using 16S rRNA metasequencing. Then, S. hominis isolates were obtained by culturomics from these microbiota samples and the C-S lyase activity was measured by spectrofluorometry in protein crude extracts.

RESULTS

The evaluation of the odour intensity revealed that within the panel, two groups were significantly distinct. A non-odorous group and a malodorous one with volunteers having unpleasant odours. The 16S rRNA metasequencing reveals differences in bacterial communities between the two groups with a significant increase in the relative abundance of S. hominis in the malodorous group compared with the non-odorous one. The C-S lyase activities measured on S. hominis sampled on volunteers from the two groups demonstrate that for an equivalent quantity of protein, this enzymatic activity is significantly higher for the samples originating from the malodorous group.

CONCLUSION

Hence, this study demonstrates that beyond the increase of S. hominis relative abundance, the C-S lyase enzymatic activity of this bacteria is also higher in volunteers with unpleasant axillary odours.

Microbial interactions shaping host attractiveness: insights into dynamic behavioral relationships

Insects discern the presence of hosts (host plants) by integrating chemosensory, gustatory, and visual cues, with olfaction playing a pivotal role in this process. Among these factors, volatile signals produced by host-associated microbial communities significantly affect insect attraction. Microorganisms are widely and abundantly found on the surfaces of humans, plants, and insects. Notably, these microorganisms can metabolize compounds from the host surface and regulate the production of characteristic volatiles, which may guide the use of host microorganisms to modulate insect behavior. Essentially, the attraction of hosts to insects is intricately linked to the presence of their symbiotic microorganisms. This review underscores the critical role of microorganisms in shaping the dynamics of attractiveness between insects and their hosts.

Sweat Protects against Contact Hypersensitivity: Transient Sweat Suppression Compromises Skin Barrier Function in Mice

Although subtle barrier defects may facilitate allergen penetration, thereby enabling allergic sensitization, the relationship between sweating disturbance and skin barrier function is unknown. However, many studies on contact hypersensitivity in mice examined ear skin, which does not sweat, instead of the footpad, where sweating is uniquely present. In this study, we assessed whether sweat suppression in the footpad before hapten application provoked a skin barrier abnormality and reduced inflammatory thresholds to topical haptens. Mice without any genetic skin barrier dysfunction displayed markedly reduced inflammatory thresholds to haptens under transient sweat suppression before hapten application. Epicutaneously applied haptens penetrated the skin more robustly in the presence of sweat suppression compared with that in its absence, although this increase was abolished by exposure to high-humidity conditions. These mice displayed a subtle atopic dermatitis-like inflammation mediated by type 2 response-dominant inflammation and increased IgE responses, mimicking some events occurring in nonlesional atopic dermatitis skin in humans and in murine models. These lesions were dramatically attenuated by exposure to high-humidity conditions. In our model, hapten sensitization does not require mechanical injury, explaining why sensitization occurs through nonlesional atopic dermatitis skin. Awareness of the importance of preserving sweating responses is essential to prevent occupational contact dermatitis and atopic dermatitis.

Wearable electrochemical biosensors to measure biomarkers with complex blood-to-sweat partition such as proteins and hormones

Smart electronic devices based on micro-controllers, also referred to as fashion electronics, have raised wearable technology. These devices may process physiological information to facilitate the wearer's immediate biofeedback in close contact with the body surface. Standard market wearable devices detect observable features as gestures or skin conductivity. In contrast, the technology based on electrochemical biosensors requires a biomarker in close contact with both a biorecognition element and an electrode surface, where electron transfer phenomena occur. The noninvasiveness is pivotal for wearable technology; thus, one of the most common target tissues for real-time monitoring is the skin. Noninvasive biosensors formats may not be available for all analytes, such as several proteins and hormones, especially when devices are installed cutaneously to measure in the sweat. Processes like cutaneous transcytosis, the paracellular cell–cell unions, or even reuptake highly regulate the solutes content of the sweat. This review discusses recent advances on wearable devices based on electrochemical biosensors for biomarkers with a complex blood-to-sweat partition like proteins and some hormones, considering the commented release regulation mechanisms to the sweat. It highlights the challenges of wearable epidermal biosensors (WEBs) design and the possible solutions. Finally, it charts the path of future developments in the WEBs arena in converging/emerging digital technologies.

Biological and Chemical Processes that Lead to Textile Malodour Development

The development of malodour on clothing is a well-known problem with social, economic and ecological consequences. Many people still think malodour is the result of a lack of hygiene, which causes social stigma and embarrassment. Clothing is washed more frequently due to odour formation or even discarded when permastink develops. The malodour formation process is impacted by many variables and processes throughout the textile lifecycle. The contact with the skin with consequent transfer of microorganisms, volatiles and odour precursors leads to the formation of a distinctive textile microbiome and volatilome. The washing and drying processes further shape the textile microbiome and impact malodour formation. These processes are impacted by interindividual differences and fabric type as well. This review describes the current knowledge on the volatilome and microbiome of the skin, textile and washing machine, the multiple factors that determine malodour formation on textiles and points out what information is still missing.

The Detection of Wound Infection by Ion Mobility Chemical Analysis

Surgical site infection represents a large burden of care in the National Health Service. Current methods for diagnosis include a subjective clinical assessment and wound swab culture that may take several days to return a result. Both techniques are potentially unreliable and result in delays in using targeted antibiotics. Volatile organic compounds (VOCs) are produced by micro-organisms such as those present in an infected wound. This study describes the use of a device to differentiate VOCs produced by an infected wound vs. colonised wound. Malodourous wound dressings were collected from patients, these were a mix of post-operative wounds and vascular leg ulcers. Wound microbiology swabs were taken and antibiotics commenced as clinically appropriate. A control group of soiled, but not malodorous wound dressings were collected from patients who had a split skin graft (SSG) donor site. The analyser used was a G.A.S. GC-IMS. The results from the samples had a sensitivity of 100% and a specificity of 88%, with a positive predictive value of 90%. An area under the curve (AUC) of 91% demonstrates an excellent ability to discriminate those with an infected wound from those without. VOC detection using GC-IMS has the potential to serve as a diagnostic tool for the differentiation of infected and non-infected wounds and facilitate the treatment of wound infections that is cost effective, non-invasive, acceptable to patients, portable, and reliable.

Advancements in Non-Invasive Biological Surface Sampling and Emerging Applications

Biological surfaces such as skin and ocular surface provide a plethora of information about the underlying biological activity of living organisms. However, they pose unique problems arising from their innate complexity, constant exposure of the surface to the surrounding elements, and the general requirement of any sampling method to be as minimally invasive as possible. Therefore, it is challenging but also rewarding to develop novel analytical tools that are suitable for in vivo and in situ sampling from biological surfaces. In this context, wearable extraction devices including passive samplers, extractive patches, and different microextraction technologies come forward as versatile, low-invasive, fast, and reliable sampling and sample preparation tools that are applicable for in vivo and in situ sampling. This review aims to address recent developments in non-invasive in vivo and in situ sampling methods from biological surfaces that introduce new ways and improve upon existing ones. Directions for the development of future technology and potential areas of applications such as clinical, bioanalytical, and doping analyses will also be discussed. These advancements include various types of passive samplers, hydrogels, and polydimethylsiloxane (PDMS) patches/microarrays, and other wearable extraction devices used mainly in skin sampling, among other novel techniques developed for ocular surface and oral tissue/fluid sampling.

Stable Antimicrobial Activity Achieved via Immobilization of Quaternary Ammonium Chloride on Hair

　Dandruff and underarm malodor are caused by microorganisms. Personal hygiene products that contain various types of antimicrobial agents are available and are used for the prevention and alleviation of these conditions. However, their effects are not significant and often do not last long. Working toward a solution, hair was treated with thioglycolic acid, a reducing agent, and then with [2-(acryloyloxy)ethyl] trimethylammonium chloride to covalently bond and immobilize quaternary ammonium chloride (QAC) to hair shafts. Fourier transform infrared analysis confirmed the bonding of QAC. Time-kill assays were performed to evaluate the antimicrobial activities against two yeast strains responsible for dandruff, two bacterial strains responsible for underarm malodor, and two typical bacterial skin microflora strains. The time- kill assays revealed the antimicrobial effects of QAC against all tested microorganisms. Washing with detergents decreased the antimicrobial effects compared to hair not washed with detergent. This method could potentially replace personal hygiene products, such as shampoos and antiperspirants, which act as antimicrobial agents in the prevention and alleviation of dandruff and underarm malodor.

The Association of the Skin Microbiota With Health, Immunity, and Disease

The human skin is densely colonized by a highly diverse microbiota comprising all three domains of life. Long believed to represent mainly a source of infection, the human skin microbiota is nowadays well accepted as an important driver of human (skin) health and well-being. This microbiota is influenced by many host and environmental factors and interacts closely with the skin immune system. Although cause and effect are usually difficult to discriminate, changes in the skin microbiota clearly play a role in the pathobiology of many types of skin disease and cosmetic disorders. Consequently, treatment and prevention strategies have to respect this role, rendering pre- and probiotic and even transplantation therapies an additional option to the use of antibiotics.

The Microbiota of the Human Skin

The aim of this chapter is to sum up important progress in the field of human skin microbiota research that was achieved over the last years.The human skin is one of the largest and most versatile organs of the human body. Owing to its function as a protective interface between the largely sterile interior of the human body and the highly microbially contaminated outer environment, it is densely colonized with a diverse and active microbiota. This skin microbiota is of high importance for human health and well-being. It is implicated in several severe skin diseases and plays a major role in wound infections. Many less severe, but negatively perceived cosmetic skin phenomena are linked with skin microbes, too. In addition, skin microorganisms, in particular on the human hands, are crucial for the field of hygiene research. Notably, apart from being only a potential source of disease and contamination, the skin microbiota also contributes to the protective functions of the human skin in many ways. Finally, the analysis of structure and function of the human skin microbiota is interesting from a basic, evolutionary perspective on human microbe interactions.Key questions in the field of skin microbiota research deal with (a) a deeper understanding of the structure (species inventory) and function (physiology) of the healthy human skin microbiota in space and time, (b) the distinction of resident and transient skin microbiota members,

Hydrogel micropatches for sampling and profiling skin metabolites

Metabolites excreted by skin have a huge potential as disease biomarkers. However, due to the shortage of convenient sampling/analysis methods, the analysis of sweat has not become very popular in the clinical setting (pilocarpine iontophoresis being a prominent exception). In this report, a facile method for sampling and rapid chemical profiling of skin metabolites excreted with sweat is proposed. Metabolites released by skin (primarily the constituents of sweat) are collected into hydrogel (agarose) micropatches. Subsequently, they are extracted in an online analytical setup incorporating nanospray desorption electrospray ionization and an ion trap mass spectrometer. In a series of reference measurements, using bulk sampling and electrospray ionization mass spectrometry, various low-molecular-weight metabolites are detected in the micropatches exposed to skin. The sampling time is as short as 10 min, while the desorption time is 2 min. Technical precision of micropatch analysis varies within the range of 3-42%, depending on the sample and the method of data treatment; the best technical precision (≤10%) has been achieved while using an isotopically labeled internal standard. The limits of detection range from 7 to 278 pmol. Differences in the quantities of extracted metabolites are observed for the samples obtained from healthy individuals (intersubject variabilities: 30-89%; n = 9), which suggests that this method may have the potential to become a semiquantitative assay in clinical analysis and forensics.

Noninvasive analysis of volatile biomarkers in human emanations for health and early disease diagnosis

Early disease diagnosis is crucial for human healthcare and successful therapy. Since any changes in homeostatic balance can alter human emanations, the components of breath exhalations and skin emissions may be diagnostic biomarkers for various diseases and metabolic disorders. Since hundreds of endogenous and exogenous volatile organic compounds (VOCs) are released from the human body, analysis of these VOCs may be a noninvasive, painless, and easy diagnostic tool. Sampling and preconcentration by sorbent tubes/traps and solid-phase microextraction, in combination with GC or GC–MS, are usually used to analyze VOCs. In addition, GC–MS-olfactometry is useful for simultaneous analysis of odorants and odor quality. Direct MS techniques are also useful for the online real-time detection of VOCs. This review focuses on recent developments in sampling and analysis of volatile biomarkers in human odors and/or emanations, and discusses future use of VOC analysis.

The skin landscape in diabetes mellitus. Focus on dermocosmetic management

Background

Some relationships are established between diabetes mellitus (DM) and a series of cutaneous disorders. Specific dermatoses are markers for undiagnosed DM. Other disorders represent supervening complications in an already treated DM patient.

Objective

To review the information about dermocosmetic care products and their appropriate use in the management and prevention of dermatoses related to DM.

Method

The peer-reviewed literature and empiric findings are covered. Owing to the limited clinical evidence available for the use of dermocosmetics, a review of the routine practices and common therapies in DM-related dermatoses was conducted.

Results

Some DM-related dermatoses (acanthosis nigricans, pigmented purpuric dermatosis) are markers of macrovascular complications. The same disorders and some others (xerosis, Dupuytren’s disease) have been found to be more frequently associated with microangiopathy. Other skin diseases (alopecia areata, vitiligo) were found to be markers of autoimmunity, particularly in type 1 DM. Unsurprisingly, using dermocosmetics and appropriate skin care has shown objective improvements of some DM-related dermatoses, such effects improve the quality of life. The most common skin manifestations of DM fall along continuum between “dry skin,” xerosis, and acquired ichthyosis, occurring predominately on the shins and feet. Dermocosmetic products improve the feeling of well-being for DM patients.

Human skin volatiles: a review

Odors emitted by human skin are of great interest to biologists in many fields; applications range from forensic studies to diagnostic tools, the design of perfumes and deodorants, and the ecology of blood-sucking insect vectors of human disease. Numerous studies have investigated the chemical composition of skin odors, and various sampling methods have been used for this purpose. The literature shows that the chemical profile of skin volatiles varies greatly among studies, and the use of different sampling procedures is probably responsible for some of these variations. To our knowledge, this is the first review focused on human skin volatile compounds. We detail the different sampling techniques, each with its own set of advantages and disadvantages, which have been used for the collection of skin odors from different parts of the human body. We present the main skin volatile compounds found in these studies, with particular emphasis on the most frequently studied body regions, axillae, hands, and feet. We propose future directions for promising experimental studies on odors from human skin, particularly in relation to the chemical ecology of blood-sucking insects.