Eccrine sweat contains IL-1α, IL-1β and IL-31 and activates epidermal keratinocytes as a danger signal

Touchpad-based immunochromatographic strip for detecting the skin surface proteins

This study demonstrates, for the first time, the proof-of-concept of a novel immunosensor, a touchpad-based immunochromatographic strip, that non-invasively extracts and detects skin surface proteins. The strip was composed of a nitrocellulose membrane at the center, where a spot of anti-human IgG capture antibody was physically adsorbed. The capture antibody spot was covered with a glass fiber membrane impregnated with phosphate-buffered saline (PBS) to extract skin surface proteins, avoiding direct contact of the human skin with the capture antibodies. Skin surface IgG was detected in two steps: (1) touching the capture antibody via a glass fiber membrane containing PBS, and (2) dipping the strip into the Au-nanoparticle-labeled secondary antibody to visualize the existence of the captured skin surface IgG on the strip. We qualitatively demonstrated that using a very small amount of PBS while maintaining contact with the skin, skin surface proteins can be concentrated and detected, even with a relatively low-sensitivity immunochromatographic chip. This sensor is expected to be a potential biosensor for the non-invasive diagnosis of the integrity of human skin.

The Acari Hypothesis, IV: revisiting the role of hygiene in allergy

Allergy and its manifestations were first appreciated in the 1870 s. Today, the mechanism by which specific substances elicit allergic reactions remains poorly understood. This is problematic from a healthcare perspective because the prevalence of allergic disease and its societal costs are substantial. Regarding mechanistic understanding of allergy, a new proposal, The Acari Hypothesis, has been forwarded. The Hypothesis, borne from consideration of alpha-gal syndrome, postulates that acarians, i.e., mites and ticks, are operative agents of allergy. By way of their pathogenic payloads and salivary pattern recognition receptor(s), acarians potentiate in human hosts the generation of IgE against acarian dietary elements. Those elements account for most, if not all, known human allergens. Inasmuch as acarian-human interactions occur on human epithelial surfaces, it is to be expected factors that influence the presence and/or operation of acarians on those surfaces influence the expression of allergic diseases. In this report, it is proposed that two adaptations of catarrhine primates, i.e., Old World monkeys, apes and humans, evolved to deter acarian species: firstly, the expansion of eccrine glands across the entirety of body surface area, and, secondly, the secretion of sweat by those glands. Contemporary hygienic practices that reduce and/or disrupt the operation of eccrine glands are likely responsible for the increase in allergic disease seen today.

Microparticles in Human Perspiration as an Inflammatory Response Index

A blood component analysis is an early step for evaluating inflammatory disorders, but it can be unfeasible in some settings. This pilot study assessed whether extracellular vesicle (EV) changes in perspiration are parallel to those occurring in blood as an alternative or complementary option to diagnose an inflammatory response. In parallel studies, EVs were analyzed in perspiration and blood obtained before and after five self-contained underwater breathing apparatus (SCUBA) divers at the National Aquarium in Baltimore performed a dive to 3.98 m of sea water for 40 min, and five non-divers performed an exercise routine at ambient atmospheric pressure. The results demonstrated that microparticles (MPs) are present in perspiration, their numbers increase in the blood in response to SCUBA diving, and the interleukin (IL)-1β content increases. In contrast, while blood-borne MPs became elevated in response to terrestrial exercise, no statistically significant increases occurred in perspiration, and there were no changes in IL-1β. There were no statistically significant elevations in the exosomes in perspiration or blood in response to SCUBA diving and few changes following terrestrial exercise. These findings suggest that an MP perspiration analysis could be a non-invasive method for detecting inflammatory responses that can occur due to the oxidative stress associated with SCUBA diving.

No effect of tattoos on local sweat concentrations of select cytokines, cortisol, glucose, blood urea nitrogen, or lactate during exercise

Due to growing interest in the investigation of exercise induced sweat biomarkers to assess an individual's health and the increasing prevalence of tattoos in the world's population, investigators sought to determine whether local sweat concentrations and excretion rates of epidermal growth factor (EGF), interleukin (IL) -1α, IL-6, IL-8, cortisol, glucose, blood urea nitrogen (BUN), and lactate differ between tattooed and contralateral non-tattooed skin during exercise. Sixteen recreational exercisers [female (50%)] (age = 25-48 years) with ≥ 1 unilateral permanent tattoo [median tattoo age = 6 years, IQR = 5] on the arm/torso completed an outdoor group fitness session. There were no significant differences between tattooed and non-tattooed skin for sweat EGF, IL-1α, IL-8, cortisol, glucose, BUN, or lactate concentrations. There were no significant differences between tattooed and non-tattooed skin for sweat EGF, IL-1α, IL-8, cortisol, glucose, BUN, or lactate excretion rate. Findings suggest that permanent tattoos older than 1 year may not impact local sweat EGF, IL-1α, IL-8, cortisol, glucose, BUN, and lactate concentrations or excretion rates during exercise.Clinical trial identifier NCT04920266 was registered on June 9, 2021.

Interplay of cytokines in the pathophysiology of atopic dermatitis: insights from Murin models and human

The pathogenesis of atopic dermatitis (AD) is understood to be crucially influenced by three main factors: dysregulation of the immune response, barrier dysfunction, and pruritus. In the lesional skin of AD, various innate immune cells, including Th2 cells, type 2 innate lymphoid cells (ILC2s), and basophils, produce Th2 cytokines [interleukin (IL)-4, IL-5, IL-13, IL-31]. Alarmins such as TSLP, IL-25, and IL-33 are also produced by epidermal keratinocytes, amplifying type 2 inflammation. In the chronic phase, not only Th2 cells but also Th22 and Th17 cells increase in number, leading to suppression of filaggrin expression by IL-4, IL-13, and IL-22, which further deteriorates the epidermal barrier function. Dupilumab, which targets IL-4 and IL-13, has shown efficacy in treating moderate to severe AD. Nemolizumab, targeting IL-31RA, effectively reduces pruritus in AD patients. In addition, clinical trials with fezakinumab, targeting IL-22, have demonstrated promising results, particularly in severe AD cases. Conversely, in murine models of AD, several cytokines, initially regarded as promising therapeutic targets, have not demonstrated sufficient efficacy in clinical trials. IL-33 has been identified as a potent activator of immune cells, exacerbating AD in murine models and correlating with disease severity in human patients. However, treatments targeting IL-33 have not shown sufficient efficacy in clinical trials. Similarly, thymic stromal lymphopoietin (TSLP), integral to type 2 immune responses, induces dermatitis in animal models and is elevated in human AD, yet clinical treatments like tezepelumab exhibit limited efficacy. Therapies targeting IL-1α, IL-5, and IL-17 also failed to achieve sufficient efficacy in clinical trials. It has become clear that for treating AD, IL-4, IL-13, and IL-31 are relevant therapeutic targets during the acute phase, while IL-22 emerges as a target in more severe cases. This delineation underscores the necessity of considering distinct pathophysiological aspects and therapeutic targets in AD between mouse models and humans. Consequently, this review delineates the distinct roles of cytokines in the pathogenesis of AD, juxtaposing their significance in human AD from clinical trials against insights gleaned from AD mouse models. This approach will improve our understanding of interspecies variation and facilitate a deeper insight into the pathogenesis of AD in humans.

Longitudinal assessment of sweat-based TNF-alpha in inflammatory bowel disease using a wearable device

Wearable devices can non-invasively monitor patients with chronic diseases. Sweat is an easily accessible biofluid for continuous sampling of analytes, including inflammatory markers and cytokines. We evaluated a sweat sensing wearable device in subjects with and without inflammatory bowel disease (IBD), a chronic inflammatory condition of the gastrointestinal tract. Participants with an IBD related hospital admission and a C-reactive protein level above 5 mg/L wore a sweat sensing wearable device for up to 5 days. Tumor necrosis factor-alpha (TNF-α) levels were continually assessed in the sweat via the sensor, and daily in the blood. A second cohort of healthy subjects without chronic diseases wore the device for up to 48 h. Twenty-eight subjects were enrolled. In the 16 subjects with IBD, a moderate linear relationship between serum and sweat TNF-α levels was observed (R2 = 0.72). Subjects with IBD were found to have a mean sweat TNF-α level of 2.11 pg/mL, compared to a mean value of 0.19 pg/mL in 12 healthy controls (p < 0.0001). Sweat TNF-α measurements differentiated subjects with active IBD from healthy subjects with an AUC of 0.962 (95% CI 0.894-1.000). A sweat sensing wearable device can longitudinally measure key sweat-based markers of IBD. TNF-α levels in the sweat of subjects with IBD correlate with serum values, suggesting feasibility in non-invasive disease monitoring.

A fluorescence imaging technique suggests that sweat leakage in the epidermis contributes to the pathomechanism of palmoplantar pustulosis

Sweat is an essential protection system for the body, but its failure can result in pathologic conditions, including several skin diseases, such as palmoplantar pustulosis (PPP). As reduced intraepidermal E-cadherin expression in skin lesions was confirmed in PPP skin lesions, a role for interleukin (IL)-1-rich sweat in PPP has been proposed, and IL-1 has been implicated in the altered E-cadherin expression observed in both cultured keratinocytes and mice epidermis. For further investigation, live imaging of sweat perspiration on a mouse toe-pad under two-photon excitation microscopy was performed using a novel fluorescent dye cocktail (which we named JSAC). Finally, intraepidermal vesicle formation which is the main cause of PPP pathogenesis was successfully induced using our "LASER-snipe" technique with JSAC. "LASER-snipe" is a type of laser ablation technique that uses two-photon absorption of fluorescent material to destroy a few acrosyringium cells at a pinpoint location in three-dimensional space of living tissue to cause eccrine sweat leakage. These observatory techniques and this mouse model may be useful not only in live imaging for physiological phenomena in vivo such as PPP pathomechanism investigation, but also for the field of functional physiological morphology.

Passive sweat wearable: A new paradigm in the wearable landscape toward enabling "detect to treat" opportunities

Growing interest over recent years in personalized health monitoring coupled with the skyrocketing popularity of wearable smart devices has led to the increased relevance of wearable sweat-based sensors for biomarker detection. From optimizing workouts to risk management of cardiovascular diseases and monitoring prediabetes, the ability of sweat sensors to continuously and noninvasively measure biomarkers in real-time has a wide range of applications. Conventional sweat sensors utilize external stimulation of sweat glands to obtain samples, however; this stimulation influences the expression profile of the biomarkers and reduces the accuracy of the detection method. To address this limitation, our laboratory pioneered the development of the passive sweat sensor subfield, which allowed for our progress in developing a sweat chemistry panel. Passive sweat sensors utilize nanoporous structures to confine and detect biomarkers in ultra-low sweat volumes. The ability of passive sweat sensors to use smaller samples than conventional sensors enable users with sedentary lifestyles who perspire less to benefit from sweat sensor technology not previously afforded to them. Herein, the mechanisms and strategies of current sweat sensors are summarized with an emphasis on the emerging subfield of passive sweat-based diagnostics. Prospects for this technology include discovering new biomarkers expressed in sweat and expanding the list of relevant detectable biomarkers. Moreover, the accuracy of biomarker detection can be enhanced with machine learning using prediction algorithms trained on clinical data. Applying this machine learning in conjunction with multiplex biomarker detection will allow for a more holistic approach to trend predictions. This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Biosensing.

Single-cell profiling of prurigo nodularis demonstrates immune-stromal crosstalk driving profibrotic responses and reversal with nemolizumab

BACKGROUND

Prurigo nodularis (PN) is a chronic neuroimmune skin disease characterized by bilaterally distributed pruritic hyperkeratotic nodules on extremities and trunk. Neuroimmune dysregulation and chronic scratching are believed to both induce and maintain the characteristic lesions.

OBJECTIVES

This study sought to provide a comprehensive view of the molecular pathogenesis of PN at the single-cell level to identify and outline key pathologic processes and the cell types involved. Features that distinguish PN skin from the skin of patients with atopic dermatitis were of particular interest. We further aimed to determine the impact of the IL31RA antagonist, nemolizumab, and its specificity at the single-cell level.

METHODS

Single-cell RNA-sequencing of skin from 15 healthy donors and nonlesional and lesional skin from 6 patients each with PN and atopic dermatitis, combined with spatial-sequencing using the 10x Visium platform. Integration with bulk RNA-sequencing data from patients treated with nemolizumab.

RESULTS

This study demonstrates that PN is an inflammatory skin disease characterized by both keratinocyte proliferation and activation of profibrotic responses. This study also demonstrates that the COL11A1+ fibroblast subset is a major contributor to fibrosis and is predominantly found in the papillary dermis of PN skin. Activation of fibrotic responses is the main distinguishing feature between PN and atopic dermatitis skin. This study further shows the broad effect of nemolizumab on PN cell types, with a prominent effect driving COL11A1+ fibroblast and keratinocyte responses toward normal.

CONCLUSIONS

This study provides a high-resolution characterization of the cell types and cellular processes activated in PN skin, establishing PN as a chronic fibrotic inflammatory skin disease. It further demonstrates the broad effect of nemolizumab on pathological processes in PN skin.

Regional and time course differences in sweat cortisol, glucose, and select cytokine concentrations during exercise

INTRODUCTION

The use of sweat as a biofluid for non-invasive sampling and diagnostics is a popular area of research. However, concentrations of cortisol, glucose, and cytokines have not been described across anatomical regions or as time progresses throughout exercise.

PURPOSE

To determine regional and time course differences in sweat cortisol, glucose, and select cytokines (EGF, IFN-γ, IL-1β, IL-1α, IL-1ra, TNF-α, IL-6, IL-8, and IL-10).

METHODS

Sweat was collected with absorbent patches from eight subjects (24-44 y; 80.2 ± 10.2 kg) on the forehead (FH), right dorsal forearm (RDF), right scapula (RS), and right triceps (RT) at 0-25 min, 30-55 min, and 60-85 min during 90 min of cycling (~ 82% HRmax) in a heated chamber (32 °C, 50% rh). ANOVA was used to determine the effect of site and time on outcomes. Data are reported as LS means ± SE.

RESULTS

There was a significant effect of location on sweat analyte concentrations with FH having higher values than most other regions for cortisol (FH: 1.15 ± 0.08 ng/mL > RDF: 0.62 ± 0.09 ng/mL and RT: 0.65 ± 0.12 ng/mL, P = 0.02), IL-1ra (P < 0.0001), and IL-8 (P < 0.0001), but lower concentrations for glucose (P = 0.01), IL-1α (P < 0.0001), and IL-10 (P = 0.02). Sweat IL-1β concentration was higher on the RS than RT (P < 0.0001). Sweat cortisol concentration increased (25 min: 0.34 ± 0.10 ng/mL < 55 min: 0.89 ± 0.07 ng/mL < 85 min: 1.27 ± 0.07 ng/mL; P < 0.0001), while EGF (P < 0.0001), IL-1ra (P < 0.0001), and IL-6 (P = 0.02) concentrations decreased over time.

CONCLUSION

Sweat analyte concentrations varied with time of sampling and anatomical region, which is essential information to consider when conducting future work in this area.

CLINICAL TRIAL IDENTIFIER

NCT04240951 registered January 27, 2020.

Selective visuoconstructional impairment following mild COVID-19 with inflammatory and neuroimaging correlation findings

People recovered from COVID-19 may still present complications including respiratory and neurological sequelae. In other viral infections, cognitive impairment occurs due to brain damage or dysfunction caused by vascular lesions and inflammatory processes. Persistent cognitive impairment compromises daily activities and psychosocial adaptation. Some level of neurological and psychiatric consequences were expected and described in severe cases of COVID-19. However, it is debatable whether neuropsychiatric complications are related to COVID-19 or to unfoldings from a severe infection. Nevertheless, the majority of cases recorded worldwide were mild to moderate self-limited illness in non-hospitalized people. Thus, it is important to understand what are the implications of mild COVID-19, which is the largest and understudied pool of COVID-19 cases. We aimed to investigate adults at least four months after recovering from mild COVID-19, which were assessed by neuropsychological, ocular and neurological tests, immune markers assay, and by structural MRI and ¹⁸FDG-PET neuroimaging to shed light on putative brain changes and clinical correlations. In approximately one-quarter of mild-COVID-19 individuals, we detected a specific visuoconstructive deficit, which was associated with changes in molecular and structural brain imaging, and correlated with upregulation of peripheral immune markers. Our findings provide evidence of neuroinflammatory burden causing cognitive deficit, in an already large and growing fraction of the world population. While living with a multitude of mild COVID-19 cases, action is required for a more comprehensive assessment and follow-up of the cognitive impairment, allowing to better understand symptom persistence and the necessity of rehabilitation of the affected individuals.

Skin Microbiome, Metabolome and Skin Phenome, from the Perspectives of Skin as an Ecosystem

Skin is a complex ecosystem colonized by millions of microorganisms, including bacteria, fungi, and viruses. Skin microbiota is believed to exert critical functions in maintaining host skin health. Profiling the structure of skin microbial community is the first step to overview the ecosystem. However, the community composition is highly individualized and extremely complex. To explore the fundamental factors driving the complexity of the ecosystem, namely the selection pressures, we review the present studies on skin microbiome from the perspectives of ecology. This review summarizes the following: (1) the composition of substances/nutrients in the cutaneous ecological environment that are derived from the host and the environment, highlighting their proposed function on skin microbiota; (2) the features of dominant skin commensals to occupy ecological niches, through self-adaptation and microbe-microbe interactions; (3) how skin microbes, by their structures or bioactive molecules, reshape host skin phenotypes, including skin immunity, maintenance of skin physiology such as pH and hydration, ultraviolet (UV) protection, odor production, and wound healing. This review aims to re-examine the host-microbe interactions from the ecological perspectives and hopefully to give new inspiration to this field.

Barrier function of the skin and the role of fat-soluble vitamins in the correction of its disorders

The main function of the skin is to protect the body from negative environmental influences. The physical barrier permeability is mainly represented by the stratum corneum; however, other layers of the epidermis and the dermis are its important components. The mechanical strength of the skin is provided by intercellular contacts in the epidermis and structural proteins of the dermis. The chemical-biological barrier includes lipids, acids, natural moisturizing factor and antimicrobial peptides. Mucosal immunity system creates a barrier against infection. The microflora of healthy skin counteracts its colonization by pathogens and is vital for its immune functions. Physiological processes in the skin are closely related. A violation in one of them often leads to the formation of a whole cascade of pathological reactions affecting all the links of its protection. Vitamins A, D and E are used to correct impaired barrier function of the skin. The most pronounced effect of vitamin A (retinol palmitate) is the proliferation of epidermal cells and synthesis of extracellular matrix structures of the dermis; vitamin D (cholecalciferol) regulation of differentiation and suppression of excessive proliferation of keratinocytes; vitamin E (tocopherol acetate) antioxidant effect. The combined use of these vitamins in the composition of RadevitActive ointment affects all the main elements of the protection of the epidermis and dermis: strengthens the mechanical strength of the stratum corneum and dermis, stabilizes chemical and physical protection, including prevents the penetration of foreign substances and microorganisms, reduces transepidermal loss of water and electrolytes, reduces the damaging effect of UV, increases antimicrobial and antioxidant protection.

Skin immunity: dissecting the complex biology of our body's outer barrier

Our skin contributes critically to health via its role as a barrier tissue, carefully regulating passage of key substrates while also providing defense against exogenous threats. Immunological processes are integral to almost every skin function and paramount to our ability to live symbiotically with skin commensal microbes and other environmental stimuli. While many parallels can be drawn to immunobiology at other mucosal sites, skin immunity demonstrates unique features that relate to its distinct topography, chemical composition and microbial ecology. Here we provide an overview of skin as an immune organ, with reference to the broader context of mucosal immunology. We review paradigms of innate as well as adaptive immune function and highlight how skin-specific structures such as hair follicles and sebaceous glands interact and contribute to these processes. Finally, we highlight for the mucosal immunology community a few emerging areas of interest for the skin immunity field moving forward.

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.

Skin-ny deeping: Uncovering immune cell behavior and function through imaging techniques

As the largest organ of the body, the skin is a key barrier tissue with specialized structures where ongoing immune surveillance is critical for protecting the body from external insults. The innate immune system acts as first-responders in a coordinated manner to react to injury or infections, and recent developments in intravital imaging techniques have made it possible to delineate dynamic immune cell responses in a spatiotemporal manner. We review here key studies involved in understanding neutrophil, dendritic cell and macrophage behavior in skin and further discuss how this knowledge collectively highlights the importance of interactions and cellular functions in a systems biology manner. Furthermore, we will review emerging imaging technologies such as high-content proteomic screening, spatial transcriptomics and three-dimensional volumetric imaging and how these techniques can be integrated to provide a systems overview of the immune system that will further our current knowledge and lead to potential exciting discoveries in the upcoming decades.

IL-31 and IL-31 receptor expression in acute experimental canine atopic dermatitis skin lesions

BACKGROUND

To optimise the interleukin (IL)-31-blocking therapy in atopic dermatitis (AD), an understanding of the chronology in the expression of IL-31 and its receptor (IL-31RA) is needed.

HYPOTHESIS/OBJECTIVES

(i) To assess the chronological expression of IL-31 in canine AD skin lesions, (ii) to compare it with serum IL-31 levels and macroscopic skin lesion scores, and (iii) to determine the identity of IL-31- and IL-31RA-positive cells.

ANIMALS

Four atopic dogs sensitised to house dust mites.

METHODS AND MATERIALS

Skin and blood samples were obtained 0 h, 24 h, 48 and 96 h after allergen provocation. IL-31 and IL-31RA single-staining immunofluorescence (IF), as well as IL-31/CD3, IL-31/CD4 and IL-31RA/β3-tubulin double-staining IF were performed. The IL-31-positive cells were counted subjectively.

RESULTS

The peak IL-31 expression for three of four dogs occurred 24 h or 48 h postchallenge; it started to decrease at 96 h. There was no significant correlation between the IL-31 expression scores and the serum IL-31 concentrations or the macroscopic skin lesion scores (P = 0.35 and P = 0.36, respectively). The majority of IL-31-positive cells were positive for CD3 (range 91-100%) and CD4 (range 63-100%), indicating that they were helper T (Th) cells. Unexpectedly, sebaceous glands were strongly immunolabelled with IL-31; the extinction of this positivity after immunoabsorption with IL-31 further supported the validity of this immunostaining. The IL-31RA was visualised on keratinocytes and a small proportion of dermal nerves.

CONCLUSIONS AND CLINICAL IMPORTANCE

The early and transient production of IL-31 by Th cells supports the concept of using IL-31 inhibiting strategies as a proactive therapy to prevent flares of AD skin lesions.

Five Functional Aspects of the Epidermal Barrier

The epidermis is a living, multilayered barrier with five functional levels, including a physical, a chemical, a microbial, a neuronal, and an immune level. Altogether, this complex organ contributes to protect the host from external aggression and to preserve its integrity. In this review, we focused on the different functional aspects.

Temporal profiling of cytokines in passively expressed sweat for detection of infection using wearable device

This work presents the viability of passive eccrine sweat as a functional biofluid toward tracking the human body's inflammatory response. Cytokines are biomarkers that orchestrate the manifestation and progression of an infection/inflammatory event. Hence, noninvasive, real-time monitoring of cytokines can be pivotal in assessing the progression of infection/inflammatory event, which may be feasible through monitoring of host immune markers in eccrine sweat. This work is the first experimental proof demonstrating the ability to detect inflammation/infection such as fever, FLU directly from passively expressed sweat in human subjects using a wearable "SWEATSENSER" device. The developed SWEATSENSER device demonstrates stable, real-time monitoring of inflammatory cytokines in passive sweat. An accuracy of >90% and specificity >95% was achieved using SWEATSENSER for a panel of cytokines (interleukin-6, interleukin-8, interleukin-10, and tumor necrosis factor-α) over an analytical range of 0.2-200 pg mL-1. The SWEATSENSER demonstrated a correlation of Pearson's r > 0.98 for the study biomarkers in a cohort of 26 subjects when correlated with standard reference method. Comparable IL-8 levels (2-15 pg mL-1) between systemic circulation (serum) and eccrine sweat through clinical studies in a cohort of 15 subjects, and the ability to distinguish healthy and sick (infection) cohort using inflammatory cytokines in sweat provides pioneering evidence of the SWEATSENSER technology for noninvasive tracking of host immune response biomarkers. Such a wearable device can offer significant strides in improving prognosis and provide personalized therapeutic treatment for several inflammatory/infectious diseases.

Tuning SLOCK toward Chronic Disease Diagnostics and Management: Label-free Sweat Interleukin-31 Detection

SLOCK (sensor for circadian clock) is an electrochemical sweat-based biosensing platform designed for the diagnosis and management of circadian abnormalities. Previously, the SLOCK platform was designed to detect adrenal steroids, cortisol, and DHEA for tracking the circadian rhythm. This work aims at tuning this SLOCK platform toward the detection of the cytokine, interleukin-31, for building a noninvasive, chronic disease diagnostics and management platform. This research provides a detailed characterization of the sensing surface and immunochemistry. The results show that SLOCK has good sensitivity to IL-31 concentrations in synthetic and human sweat. The limit of detection is 50 and 100 pg/mL for synthetic and human sweat, respectively. The dynamic range of the system is 50-1000 pg/mL, which encompasses the physiological ranges of 150-620 pg/mL. This is the first demonstration of sweat-based, label-free, electrochemical detection of IL-31. In addition to this, the data show good correlation (R 2 > 0.95) for the signal sensitivity to biomarker concentration. Finally, cross-reactivity studies highlight the specificity of SLOCK even in the presence of highly cross-reactive species. Thus, this novel SLOCK biosensor can be successfully used to track IL-31 in a sensitive and noninvasive manner and could be used to identify chronic pathophysiologies present in the body.

Nuclear IL-33 Plays an Important Role in IL-31‒Mediated Downregulation of FLG, Keratin 1, and Keratin 10 by Regulating Signal Transducer and Activator of Transcription 3 Activation in Human Keratinocytes

IL-33, a chromatin-associated multifunctional cytokine, is implicated in the pathogenesis of atopic dermatitis (AD), an inflammatory skin disorder characterized by skin barrier dysfunction. IL-33 accumulates in the nuclei of epidermal keratinocytes (KCs) in AD lesions. However, it is unclear whether nuclear IL-33 directly contributes to the pathogenesis of AD. IL-31, a pruritogenic cytokine primarily produced by T helper type 2 cells, is elevated in AD lesions and promotes AD development by suppressing KC differentiation and inducing itching. In this study, we investigated the involvement of nuclear IL-33 in IL-31‒mediated suppression of KC differentiation. In monolayer cultures and living skin equivalent, IL-31 increased the expression of full-length IL-33 and the phosphorylation of signal transducer and activator of transcription 3 (STAT3) in the nuclei of human KCs, which in turn downregulated the expression of differentiation markers. We found that IL-31 and IL-4/IL-13 use very similar mechanisms to inhibit KC differentiation: nuclear IL-33 combines with phosphorylated STAT3 and functions as a STAT3 transcription cofactor, promoting phosphorylated STAT3 binding to the FLG promoter to inhibit its transcription; moreover, the nuclear IL-33/phosphorylated STAT3 complex drives the downregulation of keratin 1 and keratin 10 by reducing the availability of the transcription factor RunX1. Therefore, nuclear IL-33 plays an important role in IL-31‒mediated differentiation suppression by regulating STAT3 activation in human KCs.

Interleukin-31 and Pruritic Skin

Skin inflammation often evokes pruritus, which is the major subjective symptom in many inflammatory skin diseases such as atopic dermatitis and prurigo nodularis. Pruritus or itch is a specific sensation found only in the skin. Recent studies have stressed the pivotal role played by interleukin-31 (IL-31) in the sensation of pruritus. IL-31 is produced by various cells including T helper 2 cells, macrophages, dendritic cells and eosinophils. IL-31 signals via a heterodimeric receptor composed of IL-31 receptor A (IL-31RA) and oncostatin M receptor β. Recent clinical trials have shown that the anti-IL-31RA antibody nemolizumab can successfully decrease pruritus in patients with atopic dermatitis and prurigo nodularis. The IL-31 pathway and pruritic skin are highlighted in this review article.

Itch intensity in prurigo nodularis is closely related to dermal interleukin-31, oncostatin M, IL-31 receptor alpha and oncostatin M receptor beta

Prurigo nodularis (PN) is a chronic skin dermatosis with hyperkeratotic and intensely pruritic nodules. Managing PN-associated itch is difficult because its aetiology is still unknown. This study aimed to investigate the correlation between itch intensity in PN and the expression of a pruritogenic cytokine interleukin (IL)-31, its receptor complex components IL-31 receptor α (IL-31RA) and oncostatin M receptor β (OSMRβ), and oncostatin M (OSM), which is a ligand of OSMR β, through immunofluorescence staining examination. Itch intensity in PN was closely correlated with the number of dermal IL-31(+) cells (Spearman's r = 0.551, p < 0.05), dermal IL-31RA(+) cells (r = 0.475, p < 0.05) and dermal OSM(+) cells (r = 0.505, p < 0.05). In addition, the number of dermal OSMRβ (+) cells was increased in PN (t test, p < 0.05), despite not being correlated with itch intensity (Spearman's r = 0.375, p > 0.05). Major cellular sources of dermal IL-31 were T cells (27.0% of total IL-31-expressing cells) and macrophages (35.0%), while those of OSM were mainly T cells (49.8%) and mast cells (26.8%). IL-31RA-expressing dermal cells were mostly mast cells (49.3%) and macrophages (36.6%), and OSMRβ was mainly expressed by macrophages (51.8%) in the dermis. These findings indicate that IL-31 (mainly from macrophages and T cells) and OSM (principally from T cells and mast cells) stimulate dermal cells expressing IL-31RA and OSMRβ (e.g. macrophages), which may further promote itch and inflammation in PN. This complex dermal milieu of cell/cytokine/receptor network can be a therapeutic target for PN-associated itch.

Skin tape sampling technique identifies proinflammatory cytokines in atopic dermatitis skin

BACKGROUND

Monitoring the effects of biologic therapies in skin diseases will benefit from alternative noninvasive skin sampling techniques to evaluate immune pathways in diseased tissue early and longitudinally.

OBJECTIVE

To establish a minimally invasive profiling of skin cytokines for diagnosis, therapeutic response monitoring, and clinical research in atopic dermatitis (AD) and other skin diseases, particularly in pediatric cohorts.

METHODS

We developed a novel method for cytokine profiling in the epidermis using skin tape strips (STSs) in a setting designed to maximize the efficiency of protein extraction from STSs. This method was applied to analyze STS protein extracts from the lesional skin of children having AD (n = 41) and normal, healthy controls (n = 22). A total of 20 cytokines were probed with the ultrasensitive Mesoscale multiplex cytokine assay.

RESULTS

A significant increase in interleukin (IL)-1b (P < .01), IL-18 (P < .001), and IL-8 (P < .001) with a decrease in IL-1a (P < .001) in the stratum corneum of AD lesional skin was found. Concurrently, an increase in markers associated with type 2 inflammatory response was readily detectable in AD lesional skin, including C-C motif chemokine ligand (CCL) 22, CCL 17, and thymic stromal lymphopoietin (TSLP). The levels of IL-1b, IL-18, and TSLP exhibited positive correlations with the AD severity index (Scoring AD index) and skin transepidermal water loss (TEWL), whereas an inverse correlation between IL-1a and Scoring AD index and IL-1a and TEWL was found. The levels of CCL17, CCL22, TSLP, IL-22, and IL-17a correlated with skin TEWL measurements.

CONCLUSION

Using minimally invasive STS analysis, we identified cytokine profiles easily sampled in AD lesional skin. The expression of these markers correlated with disease severity and reflected changes in TEWL in lesional skin. These markers suggest new response assessment targets for AD skin.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03168113.

Global warming, heat-related illnesses, and the dermatologist

Global warming, provoked by the greenhouse effect of high levels of atmospheric gases (most notably carbon dioxide and methane), directly threatens human health and survival. Individuals vary in their capacity to tolerate episodes of extreme heat. Because skin is the organ tasked with heat dissipation, it is important for dermatologists to be versed in the physiology of cutaneous heat dissipation and cognizant of clinical settings in which the skin’s thermoregulatory responses may be impaired. When the external temperature is lower than that of the skin, the skin releases internal heat through direct thermal exchange with the environment, a process that is aided by an expansion of cutaneous blood flow and eccrine sweating. Cooling through the evaporation of sweat is effective even when the external temperature exceeds that of skin. Many factors, including environmental and physiological (e.g., age and sex), and pathological (e.g., preexisting illnesses, disorders of eccrine function, and medications) considerations, affect the skin’s capacity to thermoregulate. Identification of individuals at increased risk for heat-related morbidity and mortality will become increasingly important in the care of patients.

Physiological mechanisms determining eccrine sweat composition

Purpose

The purpose of this paper is to review the physiological mechanisms determining eccrine sweat composition to assess the utility of sweat as a proxy for blood or as a potential biomarker of human health or nutritional/physiological status.

Methods

This narrative review includes the major sweat electrolytes (sodium, chloride, and potassium), other micronutrients (e.g., calcium, magnesium, iron, copper, zinc, vitamins), metabolites (e.g., glucose, lactate, ammonia, urea, bicarbonate, amino acids, ethanol), and other compounds (e.g., cytokines and cortisol).

Results

Ion membrane transport mechanisms for sodium and chloride are well established, but the mechanisms of secretion and/or reabsorption for most other sweat solutes are still equivocal. Correlations between sweat and blood have not been established for most constituents, with perhaps the exception of ethanol. With respect to sweat diagnostics, it is well accepted that elevated sweat sodium and chloride is a useful screening tool for cystic fibrosis. However, sweat electrolyte concentrations are not predictive of hydration status or sweating rate. Sweat metabolite concentrations are not a reliable biomarker for exercise intensity or other physiological stressors. To date, glucose, cytokine, and cortisol research is too limited to suggest that sweat is a useful surrogate for blood.

Conclusion

Final sweat composition is not only influenced by extracellular solute concentrations, but also mechanisms of secretion and/or reabsorption, sweat flow rate, byproducts of sweat gland metabolism, skin surface contamination, and sebum secretions, among other factors related to methodology. Future research that accounts for these confounding factors is needed to address the existing gaps in the literature.

Electronic supplementary material

The online version of this article (10.1007/s00421-020-04323-7) contains supplementary material, which is available to authorized users.

Atypical Presentation of Sweat Dermatitis with Review of Literature

Sweat dermatitis is a peculiar kind of irritant inflammatory dermatoses occurring due to prolonged exposure of retained sweat over the skin. It is commonly seen in hot and dry climates like tropics during summer months due to thermal stress. Typically, parchment paper or cellophane paper like scaling is seen over occluded areas of back, shoulder, and other areas. Here we have reported a varied presentation of sweat dermatitis in the form of its coexistence with miliaria rubra (impending to thermal burn). Further we have also observed co existing pityriasis versicolor and sweat dermatitis where the former has prevented the development of latter. Till date there is very little discussion on this condition, so we have tried to provide a concise review about sweat dermatitis along with its classical to atypical presentation with special emphasis on dermoscopy.

Blood contamination, a problem or a lucky chance to analyze non-invasively Myokines in mouth fluids?

Use of saliva in clinical studies are increasing to identify methods less invasive than blood sampling in search for systemic changes of biomarkers related to physical activity, aging, late aging and rehabilitation. The consensus is that the diagnostic value of whole saliva is compromised by the presence of blood, but we are looking at the contamination as a major opportunity for non-invasive analyses of serological biomarkers. The aim of this preliminary study was to evaluate the presence of serum in mouth fluids of healthy seniors and the eventual changes after a modest trauma, i.e., tooth brushing. Seven heathy persons, aged more than 65 years, drooling saliva in a test tube provided the fluids for the analyses. After low speed centrifugation, small aliquots of supernatants were frozen in liquid nitrogen and stored at -80° until use. Aliquots were thawed and used for quantification by the Lowry method of total proteins and by colorimetric ELISA of serum albumin, fibrinogen and lysozyme. Hemoglobin content was quantified by Spectrophotometry. Adjustment of saliva dilution, after a preliminary test, increased the homogeneity of the analytes’ content determined by colorimetric ELISA. The control reference to judge the quantity of serum in saliva was a pool of sera from age-matched healthy persons. Saliva collected from the seven healthy elderly person before and after tooth-and-gum, brushing presented measurable amount of the analytes, including fibrinogen, a minor component of the pooled sera. Tooth brushing did not induced statistically significant difference in analytes’ contents, suggesting that a measurable blood contamination is a frequent event in elderly persons. In conclusion, fibrinogen analysis in saliva is a promising approach to quantify serological biomarkers by a non-invasive procedure that will increase acceptability and frequency of analyses during follow-up in aging and rehabilitation.

Sweat as a Source of Next-Generation Digital Biomarkers

Sweat has been associated with health and disease ever since it was linked to high body temperature and exercise. It contains a broad range of electrolytes, proteins, and lipids, and therefore hosts a broad panel of potential noninvasive biomarkers. The development of novel smartphone-based biosensors will enable a more sophisticated, patient-driven sweat analysis. This will provide a broad range of novel digital biomarkers. Digital biomarkers are of increasing interest because they deliver various relevant longitudinal health data. To date, investigations on digital biomarkers have focused on creating objective measurements of function. Sweat analysis using smartphone-based biosensors has the potential to provide initial noninvasive metabolic feedback and therefore represents a promising complement and a source for next-generation digital biomarkers. From this viewpoint, we discuss state-of-the-art sweat research, focusing on the clinical implementation of sweat in medicine. Sweat provides biomarkers that represent direct metabolic feedback and is therefore expected to be the next generation of digital biomarkers. With regard to its broad application in various fields of medicine, we see a clear need to evolve the internet-enabled field of sweat expertise: iSudorology.

Architecture of antimicrobial skin defense

The skin is the largest and the most exposed organ in the body and its defense is regulated at several anatomical levels. Here, we explore how skin layers, including the epidermis, dermis, adipose tissue, and skin appendages, as well as cutaneous microbiota, contribute to the function of skin antimicrobial defense. We highlight recent studies that reveal the differential and complementary responses of skin layers to bacterial, viral, and fungal infection. In particular, we focus on key soluble mediators in the layered skin defense, such as antimicrobial peptides, as well as on lipid antimicrobials, cytokines, chemokines, and barrier-maintaining molecules. We include our own evaluative analyses of transcriptomic datasets of human skin to map the involvement of antimicrobial peptides in skin protection under both steady state and infectious conditions. Furthermore, we explore the versatility of the mechanisms underlying skin defense by highlighting the role of the immune and nervous systems in their interaction with cutaneous microbes, and by illustrating the multifunctionality of selected antimicrobial peptides in skin protection.

Physiology of sweat gland function: The roles of sweating and sweat composition in human health

The purpose of this comprehensive review is to: 1) review the physiology of sweat gland function and mechanisms determining the amount and composition of sweat excreted onto the skin surface; 2) provide an overview of the well-established thermoregulatory functions and adaptive responses of the sweat gland; and 3) discuss the state of evidence for potential non-thermoregulatory roles of sweat in the maintenance and/or perturbation of human health. The role of sweating to eliminate waste products and toxicants seems to be minor compared with other avenues of excretion via the kidneys and gastrointestinal tract; as eccrine glands do not adapt to increase excretion rates either via concentrating sweat or increasing overall sweating rate. Studies suggesting a larger role of sweat glands in clearing waste products or toxicants from the body may be an artifact of methodological issues rather than evidence for selective transport. Furthermore, unlike the renal system, it seems that sweat glands do not conserve water loss or concentrate sweat fluid through vasopressin-mediated water reabsorption. Individuals with high NaCl concentrations in sweat (e.g. cystic fibrosis) have an increased risk of NaCl imbalances during prolonged periods of heavy sweating; however, sweat-induced deficiencies appear to be of minimal risk for trace minerals and vitamins. Additional research is needed to elucidate the potential role of eccrine sweating in skin hydration and microbial defense. Finally, the utility of sweat composition as a biomarker for human physiology is currently limited; as more research is needed to determine potential relations between sweat and blood solute concentrations.

The skin transcriptome in hidradenitis suppurativa uncovers an antimicrobial and sweat gland gene signature which has distinct overlap with wounded skin

Hidradenitis suppurativa (HS) is a debilitating chronic inflammatory skin disease resulting in non-healing wounds affecting body areas of high hair follicle and sweat gland density. The pathogenesis of HS is not well understood but appears to involve dysbiosis-driven aberrant activation of the innate immune system leading to excessive inflammation. Marked dysregulation of antimicrobial peptides and proteins (AMPs) in HS is observed, which may contribute to this sustained inflammation. Here, we analyzed HS skin transcriptomes from previously published studies and integrated these findings through a comparative analysis with a published wound healing data set and with immunofluorescence and qPCR analysis from new HS patient samples. Among the top differently expressed genes between lesional and non-lesional HS skin were members of the S100 family as well as dermcidin, the latter known as a sweat gland-associated AMP and one of the most downregulated genes in HS lesions. Interestingly, many genes associated with sweat gland function, such as secretoglobins and aquaporin 5, were decreased in HS lesional skin and we discovered that these genes demonstrated opposite expression profiles in healing skin. Conversely, HS lesional and wounded skin shared a common gene signature including genes encoding for S100 proteins, defensins, and genes encoding antiviral proteins. Overall, our results suggest that the pathogenesis of HS may be driven by changes in AMP expression and altered sweat gland function, and may share a similar pathology with chronic wounds.

Collection of the Abstracts of the 2019Sp PMD: Translational Myology and Mobility Medicine

The Interdepartmental Research Centre of Myology (CIR-Myo), Department of Biomedical Sciences, University of Padova, Italy and the A&C M-C Foundation for Translational Myology, Padova, Italy organized with the scientific support of Helmut Kern, Jonathan C. Jarvis, Viviana Moresi, Marco Narici, Feliciano Protasi, Marco Sandri and Ugo Carraro, the 2019SpringPaduaMuscleDays: Translational Myology and Mobility Medicine, an International Conference held March 28-30, 2019 in Euganei Hills and Padova (Italy). Presentations and discussions of the Three Physiology Lectures and of the seven Sessions (I: Spinal Cord Neuromodulation and h-bFES in SC; II: Muscle epigenetics in aging and myopathies; III: Experimental approaches in animal models; IV: Face and Voice Rejuvenation; V: Muscle Imaging; VI: Official Meeting of the EU Center of Active Aging; VII: Early Rehabilitation after knee and hip replacement) were at very high levels. This was true in the past and will be true in future events thanks to researchers and clinicians who were and are eager to attend the PaduaMuscleDays.

Sweat is a most efficient natural moisturizer providing protective immunity at points of allergen entry

Although there is a growing acceptance that sweat could play a detrimental role in various allergic skin diseases, the possibility that sweat is also involved in maintenance of skin hydration and skin-specific immune responses has not been acknowledged. We initially describe physiological role of sweat in both maintaining skin hydration and thermoregulation. The purpose of this article is to provide the reader with objective evidence that sweating is intimately linked to vital stratum corneum barrier function and usefulness of application of moisturizers in clinical care of allergic skin diseases. This review also covers how sweating disturbance would leave the skin vulnerable to the development of various allergic skin diseases, such as atopic dermatitis. New therapeutic approaches would specifically target such sweating disturbance in these allergic skin diseases.

Sweat allergy

Sweat allergy is defined as a type I hypersensitivity against the contents of sweat, and is specifically observed in patients with atopic dermatitis (AD) and cholinergic urticaria (CholU). The allergic reaction is clinically revealed by positive reactions in the intradermal skin test and the basophil histamine release assay by sweat. A major histamine-releasing antigen in sweat, MGL_1304, has been identified. MGL_1304 is produced at a size of 29 kDa by Malassezia (M.) globosa and secreted into sweat after being processed and converted into the mature form of 17 kDa. It induces significant histamine release from basophils of patients with AD and/or CholU with MGL_1304-specific IgE, which is detected in their sera. Patients with AD also show cross-reactivity to MGL_1304-homologs in Malassezia restricta and Malassezia sympodialis, but MGL_1304 does not share cross antigenicity with human intrinsic proteins. Malassezia or its components may penetrate the damaged epidermis of AD lesions and interact with the skin immune system, resulting in the sensitization and reaction to the fungal antigen. As well as the improvement of impaired barrier functions by topical interventions, approaches such as anti-microbial treatment, the induction of tolerance and antibody/substance neutralizing the sweat antigen may be beneficial for the patients with intractable AD or CholU due to sweat allergy. The identification of antigens other than MGL_1304 in sweat should be the scope for future studies, which may lead to better understanding of sweat allergy and therapeutic innovations.

Eccrine Sweat as a Biofluid for Profiling Immune Biomarkers

Purpose

Sweat is a relatively unexplored biofluid for diagnosis and monitoring of disease states. In this study, the proteomic profiling of immune‐related biomarkers from healthy individuals are presented.

Experimental Design

Eccrine sweat samples are collected from 50 healthy individuals. LC‐MS/MS is performed on two pools of sweat samples from five male and female participants. Individual sweat samples are analyzed by antibody isotyping microarrays (n = 49), human cytokine arrays (n = 30), and quantitative ELISAs for interleukin‐1α (n = 16), epidermal growth factor (n = 6), and angiogenin (n = 7).

Results

In sweat, 220 unique proteins are identified by shotgun analysis. Detectable antibody isotypes include IgA (100% positive; median 1230 ± 28 700 pg mL⁻¹), IgD (18%; 22.0 ± 119 pg mL⁻¹), IgG1 (96%; 1640 ± 6750 pg mL⁻¹), IgG2 (37%; 292 ± 6810 pg mL⁻¹), IgG3 (71%; 74.0 ± 119 pg mL⁻¹), IgG4 (69%; 43.0 ± 42.0 pg mL⁻¹), and IgM (41%; 69.0 ± 1630 pg mL⁻¹). Of 42 cytokines, three are readily detected in all sweat samples (p < 0.01). The median concentration for interleukin‐1α is 352 ± 521 pg mL⁻¹, epidermal growth factor is 86.5 ± 147 pg mL⁻¹, and angiogenin is 38.3 ± 96.3 pg mL⁻¹. Multiple other cytokines are detected at lower levels.

Conclusions and Clinical Relevance

Sweat can be used for profiling antibodies and innate immune biomarkers.

A cross-sectional study of sweat-induced dermatitis during a South Indian summer: a glimpse of sweat gland-mediated cutaneous inflammation

BACKGROUND

The role of sweat gland in inflammation has not received sufficient attention. The thermal stress during the summer months in tropical areas provides an opportunity to study the morphological patterns of inflammation produced primarily by the sweat gland.

AIM

To collect clinical data on sweat-induced dermatitis during the summer months.

METHODS

A hospital-based descriptive cross-sectional study was done during the hot and humid summer months of April to June in a tertiary care institute in Puducherry. Patients clinically diagnosed with sweat-induced dermatitis (dermatitis primarily due to retention or extravasation of sweat) were included in the study. A detailed history was taken, and clinical examination was done.

RESULTS

One hundred and fifty patients were included in the study. Various typical and atypical manifestations of sweat-induced dermatitis were seen. "Sweat dermatitis" presenting with dry, hyperpigmented, fissured "parchment"-like skin, shiny "crinkled cellophane paper"-like skin, or asymptomatic hyperpigmented macules was seen. Other atypical presentations included miliaria pustulosa with "hypopyon sign" and "linear and parallel ridge pattern" of dermatitis in patients with miliaria rubra affecting the lower neck and upper chest.

CONCLUSION

A wide spectrum of sweat-induced dermatitis was seen during the summer months in a tropical region. It reflects the role of the sweat gland in cutaneous inflammation. An increased awareness of atypical manifestations is needed.

Heparinoid suppresses Der p-induced IL-1β production by inhibiting ERK and p38 MAPK pathways in keratinocytes

Epidermal keratinocytes initiate skin inflammation by activating immune cells. The skin barrier is disrupted in atopic dermatitis (AD) and epidermal keratinocytes can be exposed to environmental stimuli, such as house dust mite (HDM) allergens. We showed previously that HDM allergens activate the NLRP3 inflammasome of keratinocytes, thereby releasing pro-inflammatory cytokines. Heparinoid is an effective moisturizer for atopic dry skin. However, a recent report showed that heparinoid treatment can improve inflammation of lichen planus. Therefore, we hypothesized that it acts on epidermal keratinocytes not only as a moisturizer, but also as a suppressant of the triggers of skin inflammation. We found that HDM allergen-induced interleukin (IL)-1β release from keratinocytes was inhibited significantly by heparinoid pretreatment without affecting cell viability. However, heparinoid did not affect caspase-1 release, suggesting that heparinoid did not affect HDM allergen-induced inflammasome activation. Heparinoid treatment not only decreased intracellular levels of pro-IL-1β, but also suppressed IL-1β messenger RNA (mRNA) expression in keratinocytes. Among the intracellular signalling pathways, the activation of extracellular signal-regulated kinase and p38 pathways, which are required for IL-1β expression in keratinocytes, was inhibited by heparinoid treatment. The inhibitory effect of heparinoid on IL-1β mRNA expression was also confirmed with living skin equivalents. Our results demonstrated that heparinoid suppresses the initiation of keratinocyte-mediated skin inflammation.

Emerging role of interleukin-31 and interleukin-31 receptor in pruritus in atopic dermatitis

Atopic dermatitis (AD) is a chronic or chronically relapsing, eczematous, severely pruritic skin disorder associated with skin barrier dysfunction. The lesional skin of AD exhibits T helper 2 (T_H 2)-deviated immune reactions. Interleukin-31 (IL-31), preferentially produced from T_H 2 cells, is a potent pruritogenic cytokine, and its systemic and local administration induces scratching behavior in rodents, dogs and monkeys. Recent clinical trials have revealed that administration of an anti-IL-31 receptor antibody significantly alleviates pruritus in patients with AD. In this review, we summarize recent topics related to IL-31 and its receptor with special references to atopic itch.

[Altered Treg and IL-1A Expression in the Immune Microenvironment of Lung Squamous-cell Cancer after EGFR Blockade]

背景与目的

精确靶向表皮生长因子受体（epidermal growth factor receptor, EGFR）的治疗在肺鳞癌、口腔和肠胃癌中取得了一定疗效，但会引发系统性炎症。本实验旨在探究EGFR抑制剂治疗癌引发的肿瘤内部免疫变化。

方法

我们通过含H-ras基因逆转录病毒转染EGFR基因缺失或野生型小鼠角质细胞，将改造的细胞同源移植至小鼠以成瘤，吉非替尼治疗荷瘤小鼠，流式细胞仪检测T细胞比例与程序性死亡受体1（programmed death 1, PD-1）表达，RT-PCR检测细胞因子与趋化因子的表达。

结果

敲除EGFR基因形成的肿瘤较野生型小，并且肿瘤微环境中浸润FoxP3+调节性T细胞（regulatory cells, Treg）细胞较少，FoxP3 RNA较少，程序性死亡受体1（programmed death 1, PD-1）阳性CD4⁺细胞比例降低。表明肿瘤细胞可以自主调节肿瘤微环境。野生型成瘤模型使用吉非替尼治疗1周显示，相对于对照组肿瘤较小；在这短期的药理模型中，同样观察到FoxP3+细胞、FoxP3 RNA减少的趋势，同时IL-1A/IL-1RA比例明显升高，表明相对短暂的系统性抑制EGFR信号通路可改变靶向肿瘤的免疫微环境。

结论

肿瘤细胞自发（基因）或系统性（药理作用）的抑制EGFR信号通路可减少肿瘤的生长和肿瘤微环境中Treg的渗透。EGFR依赖性Treg细胞增强肺鳞癌的生长，是EGFR抑制剂治疗的靶标。

Interleukin-31 pathway and its role in atopic dermatitis: a systematic review

BACKGROUND

Atopic dermatitis, a chronic inflammatory disease, has a lifetime prevalence of 10-20%. Atopic dermatitis reduces quality of life, primarily due to pruritus. Interleukin-31 and its target receptor are newly discovered entities that are involved in pruritus.

PURPOSE

To summarize the current understanding of interleukin-31 and its role in atopic dermatitis, potential therapeutic interventions and future prospects.

METHODS

A systematic review was designed to identify articles related to interleukin-31 and its role in pruritus. Predefined queries containing interleukin-31 and related key terms were searched with no past date restriction, through 31 August 2016, using MEDLINE, Cochrane Controlled Trials Register, ClinicalTrials.gov and the International Clinical Trials Registry Platform Search Portal database.

RESULTS

Of 151 identified articles, 61 met eligibility criteria. Interleukin-31 receptors are expressed constitutively on the surface of keratinocytes, eosinophils and small diameter neurons. Overexpression of interleukin-31, independent of mast cells and lymphocytes, induces clinical and histological features consistent with atopic dermatitis. In addition, overexpression of interleukin-31 causes reversible alopecia. Human monoclonal interleukin-31 antagonist, CIM331, decreased pruritus in phase-I and phase-II clinical trials.

CONCLUSIONS

Interleukin-31 plays an important role in atopic dermatitis and alopecia. Inhibiting this pathway may provide an alternative to antihistamines for the pruritus of atopic dermatitis.

Working Up a Good Sweat - The Challenges of Standardising Sweat Collection for Metabolomics Analysis

INTRODUCTION

Human sweat is a complex biofluid of interest to diverse scientific fields. Metabolomics analysis of sweat promises to improve screening, diagnosis and self-monitoring of numerous conditions through new applications and greater personalisation of medical interventions. Before these applications can be fully developed, existing methods for the collection, handling, processing and storage of human sweat need to be revised. This review presents a cross-disciplinary overview of the origins, composition, physical characteristics and functional roles of human sweat, and explores the factors involved in standardising sweat collection for metabolomics analysis.

METHODS

A literature review of human sweat analysis over the past 10 years (2006-2016) was performed to identify studies with metabolomics or similarly applicable 'omics' analysis. These studies were reviewed with attention to sweat induction and sampling techniques, timing of sweat collection, sweat storage conditions, laboratory derivation, processing and analytical platforms.

RESULTS

Comparative analysis of 20 studies revealed numerous factors that can significantly impact the validity, reliability and reproducibility of sweat analysis including: anatomical site of sweat sampling, skin integrity and preparation; temperature and humidity at the sweat collection sites; timing and nature of sweat collection; metabolic quenching; transport and storage; qualitative and quantitative measurements of the skin microbiota at sweat collection sites; and individual variables such as diet, emotional state, metabolic conditions, pharmaceutical, recreational drug and supplement use.

CONCLUSION

Further development of standard operating protocols for human sweat collection can open the way for sweat metabolomics to significantly add to our understanding of human physiology in health and disease.