Eccrine sweat gland development and sweat secretion

The anoctamins: Structure and function

When activated by increase in intracellular Ca2+, anoctamins (TMEM16 proteins) operate as phospholipid scramblases and as ion channels. Anoctamin 1 (ANO1) is the Ca2+-activated epithelial anion-selective channel that is coexpressed together with the abundant scramblase ANO6 and additional intracellular anoctamins. In salivary and pancreatic glands, ANO1 is tightly packed in the apical membrane and secretes Cl-. Epithelia of airways and gut use cystic fibrosis transmembrane conductance regulator (CFTR) as an apical Cl- exit pathway while ANO1 supports Cl- secretion mainly by facilitating activation of luminal CFTR and basolateral K+ channels. Under healthy conditions ANO1 modulates intracellular Ca2+ signals by tethering the endoplasmic reticulum, and except of glands its direct secretory contribution as Cl- channel might be small, compared to CFTR. In the kidneys ANO1 supports proximal tubular acid secretion and protein reabsorption and probably helps to excrete HCO3-in the collecting duct epithelium. However, under pathological conditions as in polycystic kidney disease, ANO1 is strongly upregulated and may cause enhanced proliferation and cyst growth. Under pathological condition, ANO1 and ANO6 are upregulated and operate as secretory channel/phospholipid scramblases, partly by supporting Ca2+-dependent processes. Much less is known about the role of other epithelial anoctamins whose potential functions are discussed in this review.

Making commercial bracelet smarter with a biochemical button module

Despite the rapid development of mobile health based on wearable devices in recent years, lack of access to biochemical detection remains a vital challenge for most commercial wearable devices, which hinders the provision of effective electronic health records (EHRs) for disease control strategies, and further constraining the development of personalized precision medicine. Herein, we propose a strategy to graft biochemical detection function onto commercial bracelet. Different from the conventional development process of designing a completely new wearable biochemical device, we prefer to upgrade existing commercial wearable device to achieve simpler, faster, and more effective research and commercialization processes. An affordable and user-friendly biochemical button module has been designed that enables to integrate sensitive, specific, and rapid biochemical detection function into the idle space on the strap of the bracelet without increasing the size of the main body. This "Smart Bracelet Plus" shows the ability to simultaneously monitor physical and biochemical signals, and will serve as a reliable and systematic personal diagnostics and monitoring platform for providing real-time EHRs for disease control strategies and improving the efficiency of the healthcare system.

Customized Proteinaceous Nanoformulation for In Vivo Chemical Reprogramming

Sweat gland (SwG) regeneration is crucial for the functional rehabilitation of burn patients. In vivo chemical reprogramming that harnessing the patient's own cells in damaged tissue is of substantial interest to regenerate organs endogenously by pharmacological manipulation, which could compensate for tissue loss in devastating diseases and injuries, for example, burns. However, achieving in vivo chemical reprogramming is challenging due to the low reprogramming efficiency and an unfavorable tissue environment. Herein, this work has developed a functionalized proteinaceous nanoformulation delivery system containing prefabricated epidermal growth factor structure for on-demand delivery of a cocktail of seven SwG reprogramming components to the dermal site. Such a chemical reprogramming system can efficiently induce the conversion of epidermal keratinocytes into SwG myoepithelial cells, resulting in successful in situ regeneration of functional SwGs. Notably, in vivo chemical reprogramming of SwGs is achieved for the first time with an impressive efficiency of 30.6%, surpassing previously reported efficiencies. Overall, this proteinaceous nanoformulation provides a platform for coordinating the target delivery of multiple pharmacological agents and facilitating in vivo SwG reprogramming by chemicals. This advancement greatly improves the clinical accessibility of in vivo reprogramming and offers a non-surgical, non-viral, and cell-free strategy for in situ SwG regeneration.

Characterization of age-associated gene expression changes in mouse sweat glands

Evaporation of sweat on the skin surface is the major mechanism for dissipating heat in humans. The secretory capacity of sweat glands (SWGs) declines during aging, leading to heat intolerance in the elderly, but the mechanisms responsible for this decline are poorly understood. We investigated the molecular changes accompanying SWG aging in mice, where sweat tests confirmed a significant reduction of active SWGs in old mice relative to young mice. We first identified SWG-enriched mRNAs by comparing the skin transcriptome of Eda mutant Tabby male mice, which lack SWGs, with that of wild-type control mice by RNA-sequencing analysis. This comparison revealed 171 mRNAs enriched in SWGs, including 47 mRNAs encoding 'core secretory' proteins such as transcription factors, ion channels, ion transporters, and trans-synaptic signaling proteins. Among these, 28 SWG-enriched mRNAs showed significantly altered abundance in the aged male footpad skin, and 11 of them, including Foxa1, Best2, Chrm3, and Foxc1 mRNAs, were found in the 'core secretory' category. Consistent with the changes in mRNA expression levels, immunohistology revealed that higher numbers of secretory cells from old SWGs express the transcription factor FOXC1, the protein product of Foxc1 mRNA. In sum, our study identified mRNAs enriched in SWGs, including those that encode core secretory proteins, and altered abundance of these mRNAs and proteins with aging in mouse SWGs.

Comprehensive analysis of human tissues reveals unique expression and localization patterns of HSF1 and HSF2

Heat shock factors (HSFs) are the main transcriptional regulators of the evolutionarily conserved heat shock response. Beyond cell stress, several studies have demonstrated that HSFs also contribute to a vast variety of human pathologies, ranging from metabolic diseases to cancer and neurodegeneration. Despite their evident role in mitigating cellular perturbations, the functions of HSF1 and HSF2 in physiological proteostasis have remained inconclusive. Here, we analyzed a comprehensive selection of paraffin-embedded human tissue samples with immunohistochemistry. We demonstrate that both HSF1 and HSF2 display distinct expression and subcellular localization patterns in benign tissues. HSF1 localizes to the nucleus in all epithelial cell types, whereas nuclear expression of HSF2 was limited to only a few cell types, especially the spermatogonia and the urothelial umbrella cells. We observed a consistent and robust cytoplasmic expression of HSF2 across all studied smooth muscle and endothelial cells, including the smooth muscle cells surrounding the vasculature and the high endothelial venules in lymph nodes. Outstandingly, HSF2 localized specifically at cell-cell adhesion sites in a broad selection of tissue types, such as the cardiac muscle, liver, and epididymis. To the best of our knowledge, this is the first study to systematically describe the expression and localization patterns of HSF1 and HSF2 in benign human tissues. Thus, our work expands the biological landscape of these factors and creates the foundation for the identification of specific roles of HSF1 and HSF2 in normal physiological processes.

Revealing mitf functions and visualizing allografted tumor metastasis in colorless and immunodeficient Xenopus tropicalis

Transparent immunodeficient animal models not only enhance in vivo imaging investigations of visceral organ development but also facilitate in vivo tracking of transplanted tumor cells. However, at present, transparent and immunodeficient animal models are confined to zebrafish, presenting substantial challenges for real-time, in vivo imaging studies addressing specific biological inquiries. Here, we employed a mitf-/-/prkdc-/-/il2rg-/- triple-knockout strategy to establish a colorless and immunodeficient amphibian model of Xenopus tropicalis. By disrupting the mitf gene, we observed the loss of melanophores, xanthophores, and granular glands in Xenopus tropicalis. Through the endogenous mitf promoter to drive BRAFV600E expression, we confirmed mitf expression in melanophores, xanthophores and granular glands. Moreover, the reconstruction of the disrupted site effectively reinstated melanophores, xanthophores, and granular glands, further highlighting the crucial role of mitf as a regulator in their development. By crossing mitf-/- frogs with prkdc-/-/il2rg-/- frogs, we generated a mitf-/-/prkdc-/-/il2rg-/- Xenopus tropicalis line, providing a colorless and immunodeficient amphibian model. Utilizing this model, we successfully observed intravital metastases of allotransplanted xanthophoromas and migrations of allotransplanted melanomas. Overall, colorless and immunodeficient Xenopus tropicalis holds great promise as a valuable platform for tumorous and developmental biology research.

Sweat gland development requires an eccrine dermal niche and couples two epidermal programs

Eccrine sweat glands are indispensable for human thermoregulation and, similar to other mammalian skin appendages, form from multipotent epidermal progenitors. Limited understanding of how epidermal progenitors specialize to form these vital organs has precluded therapeutic efforts toward their regeneration. Herein, we applied single-nucleus transcriptomics to compare the expression content of wild-type, eccrine-forming mouse skin to that of mice harboring a skin-specific disruption of Engrailed 1 (En1), a transcription factor that promotes eccrine gland formation in humans and mice. We identify two concurrent but disproportionate epidermal transcriptomes in the early eccrine anlagen: one that is shared with hair follicles and one that is En1 dependent and eccrine specific. We demonstrate that eccrine development requires the induction of a dermal niche proximal to each developing gland in humans and mice. Our study defines the signatures of eccrine identity and uncovers the eccrine dermal niche, setting the stage for targeted regeneration and comprehensive skin repair.

Defining the fate trajectory of eccrine gland formation

Eccrine glands secrete water onto the surface of human skin to regulate body temperature. In this issue of Developmental Cell, Dingwall et al. dissect the transcriptional signature of developing eccrine glands, and they also uncover a unique dermal niche that is responsible for promoting eccrine gland developmental progression.

Wearing the Lab: Advances and Challenges in Skin-Interfaced Systems for Continuous Biochemical Sensing

Continuous, on-demand, and, most importantly, contextual data regarding individual biomarker concentrations exemplify the holy grail for personalized health and performance monitoring. This is well-illustrated for continuous glucose monitoring, which has drastically improved outcomes and quality of life for diabetic patients over the past 2 decades. Recent advances in wearable biosensing technologies (biorecognition elements, transduction mechanisms, materials, and integration schemes) have begun to make monitoring of other clinically relevant analytes a reality via minimally invasive skin-interfaced devices. However, several challenges concerning sensitivity, specificity, calibration, sensor longevity, and overall device lifetime must be addressed before these systems can be made commercially viable. In this chapter, a logical framework for developing a wearable skin-interfaced device for a desired application is proposed with careful consideration of the feasibility of monitoring certain analytes in sweat and interstitial fluid and the current development of the tools available to do so. Specifically, we focus on recent advancements in the engineering of biorecognition elements, the development of more robust signal transduction mechanisms, and novel integration schemes that allow for continuous quantitative analysis. Furthermore, we highlight the most compelling and promising prospects in the field of wearable biosensing and the challenges that remain in translating these technologies into useful products for disease management and for optimizing human performance.

Bioactive materials for in vivo sweat gland regeneration

Loss of sweat glands (SwGs) commonly associated with extensive skin defects is a leading cause of hyperthermia and heat stroke. In vivo tissue engineering possesses the potential to take use of the body natural ability to regenerate SwGs, making it more conducive to clinical translation. Despite recent advances in regenerative medicine, reconstructing SwG tissue with the same structure and function as native tissue remains challenging. Elucidating the SwG generation mechanism and developing biomaterials for in vivo tissue engineering is essential for understanding and developing in vivo SwG regenerative strategies. Here, we outline the cell biology associated with functional wound healing and the characteristics of bioactive materials. We critically summarize the recent progress in bioactive material-based cell modulation approaches for in vivo SwG regeneration, including the recruitment of endogenous cells to the skin lesion for SwG regeneration and in vivo cellular reprogramming for SwG regeneration. We discussed the re-establishment of microenvironment via bioactive material-mediated regulators. Besides, we offer promising perspectives for directing in situ SwG regeneration via bioactive material-based cell-free strategy, which is a simple and effective approach to regenerate SwG tissue with both fidelity of structure and function. Finally, we discuss the opportunities and challenges of in vivo SwG regeneration in detail. The molecular mechanisms and cell fate modulation of in vivo SwG regeneration will provide further insights into the regeneration of patient-specific SwGs and the development of potential intervention strategies for gland-derived diseases.

A closer look into the cellular and molecular biology of myoepithelial cells across various exocrine glands

Myoepithelial cells (MECs) are a unique subset of epithelial cells that possess several smooth muscle cell characteristics, such as a high number of actin-myosin filaments and the ability to contract. These cells are primarily located around the secretory cells of exocrine glands, including the salivary, mammary, lacrimal, and sweat glands. Their primary functions involve the construction of the basement membrane and help with secretion of gland products through contraction. So far, no comparative analysis of MECs in different exocrine glands had ever evaluated their differences. In this review, we took advantage of the various publicly available scRNAseq data from mouse exocrine glands to identify their shared and unique characteristics. The aim of this review is to compare the role of MECs in maintaining healthy glandular function, their involvement in disease states, and their regenerative capacity, with a particular emphasis on the latest research findings in these areas.

Single-Cell and Spatial Transcriptomic Analysis of Human Skin Delineates Intercellular Communication and Pathogenic Cells

Epidermal homeostasis is governed by a balance between keratinocyte proliferation and differentiation with contributions from cell-cell interactions, but conserved or divergent mechanisms governing this equilibrium across species and how an imbalance contributes to skin disease are largely undefined. To address these questions, human skin single-cell RNA sequencing and spatial transcriptomics data were integrated and compared with mouse skin data. Human skin cell-type annotation was improved using matched spatial transcriptomics data, highlighting the importance of spatial context in cell-type identity, and spatial transcriptomics refined cellular communication inference. In cross-species analyses, we identified a human spinous keratinocyte subpopulation that exhibited proliferative capacity and a heavy metal processing signature, which was absent in mouse and may account for species differences in epidermal thickness. This human subpopulation was expanded in psoriasis and zinc-deficiency dermatitis, attesting to disease relevance and suggesting a paradigm of subpopulation dysfunction as a hallmark of the disease. To assess additional potential subpopulation drivers of skin diseases, we performed cell-of-origin enrichment analysis within genodermatoses, nominating pathogenic cell subpopulations and their communication pathways, which highlighted multiple potential therapeutic targets. This integrated dataset is encompassed in a publicly available web resource to aid mechanistic and translational studies of normal and diseased skin.

Intrinsic and extrinsic factors affecting axillary odor variation. A comprehensive review

Humans produce odorous secretions from multiple body sites according to the microbiomic profile of each area and the types of secretory glands present. Because the axilla is an active, odor-producing region that mediates social communication via the sense of smell, this article focuses on the biological mechanisms underlying the creation of axillary odor, as well as the intrinsic and extrinsic factors likely to impact the odor and determine individual differences. The list of intrinsic factors discussed includes sex, age, ethnicity, emotions, and personality, and extrinsic factors include dietary choices, diseases, climate, and hygienic habits. In addition, we also draw attention to gaps in our understanding of each factor, including, for example, topical areas such as the effect of climate on body odor variation. Fundamental challenges and emerging research opportunities are further outlined in the discussion. Finally, we suggest guidelines and best practices based on the factors reviewed herein for preparatory protocols of sweat collection, data analysis, and interpretation.

Type 1 interferon signature and cytotoxic T lymphocyte activation targeted against sweat ducts in inflammatory acquired idiopathic generalized anhidrosis

BACKGROUND

Acquired idiopathic generalized anhidrosis (AIGA) leads to heat intolerance due to the loss or reduction in thermoregulatory sweating over an extensive area of the body. The pathomechanism of AIGA is still unclear but is believed to be autoimmune.

OBJECTIVES

We investigated the clinical and pathological features of inflammatory AIGA (InfAIGA) and noninflammatory AIGA (non-InfAIGA) within the skin.

METHODS

We compared anhidrotic and normohidrotic skin samples from 30 patients with InfAIGA and non-InfAIGA, as well as skin samples of melanocytic nevus as a negative control. We conducted morphometric analysis and immunohistochemical analysis of cell types and expression of inflammatory molecules (TIA1, CXCR3 and MxA). MxA expression was used as a proxy for type 1 interferon activity.

RESULTS

We found that tissue samples from patients with InfAIGA exhibited inflammation within the sweat duct and atrophy of the sweat coil, whereas patients with non-InfAIGA exhibited only atrophy of the sweat coil. Cytotoxic T lymphocyte infiltration and MxA expression were only observed in the sweat ducts of patients with InfAIGA.

CONCLUSIONS

InfAIGA is associated with increased sweat duct inflammation and sweat coil atrophy, whereas non-InfAIGA is only associated with sweat coil atrophy. These data suggest that inflammation leads to epithelial destruction of sweat ducts associated with the sweat coil atrophy and subsequent loss of function. Non-InfAIGA may be regarded as a postinflammatory state of InfAIGA. These observations indicate the contribution of both type 1 and type 2 interferons to sweat gland injury. The mechanism involved is similar to the pathomechanism of alopecia areata (AA).

Epithelial polarity-driven membrane separation but not cavitation regulates lumen formation of rat eccrine sweat glands

BACKGROUND

Each eccrine sweat gland (ESG) is a single-tubular structure with a central lumen, and the formation of hollow lumen in the initial solid cell mass is a key developmental process. To date, there are no reports on the mechanism of native ESG lumen formation.

METHODS

To investigate the lumen morphogenesis and the lumen formation mechanisms of Sprague-Dawley (SD) rat ESGs, SD rat hind-footpads at E20.5, P1-P5, P7, P9, P12, P21, P28 and P56 were obtained. The lumen morphogenesis of ESGs was examined by HE staining and immunofluorescence staining for polarity markers. The possible mechanisms of lumen formation were detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay and autophagy marker LC3B immunofluorescence staining, and further explored by ouabain intervention experiment.

RESULTS

In SD rat ESGs, the microlumen was formed at P1, and the small intact lumen with apical-basal polarity appeared at P3. The expression of apical marker F-actin, basal marker Laminin, basolateral marker E-cadherin was consistent with the timing of lumen formation of SD rat ESGs. During rat ESG development, apoptosis and autophagy were not detected. However, inhibition of Na+-K+-ATPase (NKA) with ouabain resulted in decreased lumen size, although neither the timing of lumen formation nor the expression of polarity proteins was altered.

CONCLUSIONS

Epithelial polarity-driven membrane separation but not cavitation regulates lumen formation of SD rat ESGs. NKA-regulated fluid accumulation drives lumen expansion.

Neurotransmitter signaling specifies sweat gland stem cell fate through SLN-mediated intracellular calcium regulation

Sympathetic nerves co-develop with their target organs and release neurotransmitters to stimulate their functions after maturation. Here, we provide the molecular mechanism that during sweat gland morphogenesis, neurotransmitters released from sympathetic nerves act first to promote sweat duct elongation via norepinephrine and followed by acetylcholine to specify sweat gland stem cell fate, which matches the sequence of neurotransmitter switch. Without neuronal signals during development, the basal cells switch to exhibit suprabasal (luminal) cell features. Sarcolipin (SLN), a key regulator of sarcoendoplasmic reticulum (SR) Ca 2+ -ATPase (SERCA), expression is significantly down-regulated in the sweat gland myoepithelial cells upon denervation. Loss of SLN in sweat gland myoepithelial cells leads to decreased intracellular Ca 2+ over time in response to ACh stimulation, as well as upregulation of luminal cell features. In cell culture experiments, we showed that contrary to the paradigm that elevation of Ca 2+ promote epidermal differentiation, specification of the glandular myoepithelial (basal) cells requires high Ca 2+ while lowering Ca 2+ level promotes luminal (suprabasal) cell fate. Our work highlights that neuronal signals not only act transiently for mature sweat glands to function, but also exert long-term impact on glandular stem cell specification through regulating intracellular Ca 2+ dynamics.

Electrodermal signal analysis using continuous wavelet transform as a tool for quantification of sweat gland activity in diabetic kidney disease

Sympathetic innervation of the sweat gland (SG) manifests itself electrically as electrodermal activity (EDA), which can be utilized to measure sudomotor function. Since SG exhibits similarities in structure and function with kidneys, quantification of SG activity is attempted through EDA signals. A methodology is developed with electrical stimulation, sampling frequency and signal processing algorithm. One hundred twenty volunteers participated in this study belonging to controls, diabetes, diabetic nephropathy, and diabetic neuropathy. The magnitude and time duration of stimuli is arrived by trial and error in such a way it does not influence controls but triggers SG activity in other Groups. This methodology leads to a distinct EDA signal pattern with changes in frequency and amplitude. The continuous wavelet transform depicts a scalogram to retrieve this information. Further, to distinguish between Groups, time average spectrums are plotted and mean relative energy (MRE) is computed. Results demonstrate high energy value in controls, and it gradually decreases in other Groups indicating a decline in SG activity on diabetes prognosis. The correlation for the acquired results was determined to be 0.99 when compared to the standard lab procedure. Furthermore, Cohen's d value, which is less than 0.25 for all Groups indicating the minimal effect size. Hence the obtained result is validated and statistically analyzed for individual variations. Thus this has the potential to get transformed into a device and could prevent diabetic kidney disease.

Revolutionizing Precision Medicine: Exploring Wearable Sensors for Therapeutic Drug Monitoring and Personalized Therapy

Precision medicine, particularly therapeutic drug monitoring (TDM), is essential for optimizing drug dosage and minimizing toxicity. However, current TDM methods have limitations, including the need for skilled operators, patient discomfort, and the inability to monitor dynamic drug level changes. In recent years, wearable sensors have emerged as a promising solution for drug monitoring. These sensors offer real-time and continuous measurement of drug concentrations in biofluids, enabling personalized medicine and reducing the risk of toxicity. This review provides an overview of drugs detectable by wearable sensors and explores biosensing technologies that can enable drug monitoring in the future. It presents a comparative analysis of multiple biosensing technologies and evaluates their strengths and limitations for integration into wearable detection systems. The promising capabilities of wearable sensors for real-time and continuous drug monitoring offer revolutionary advancements in diagnostic tools, supporting personalized medicine and optimal therapeutic effects. Wearable sensors are poised to become essential components of healthcare systems, catering to the diverse needs of patients and reducing healthcare costs.

Skin-Interfaced Wearable Sweat Sensors for Precision Medicine

Wearable sensors hold great potential in empowering personalized health monitoring, predictive analytics, and timely intervention toward personalized healthcare. Advances in flexible electronics, materials science, and electrochemistry have spurred the development of wearable sweat sensors that enable the continuous and noninvasive screening of analytes indicative of health status. Existing major challenges in wearable sensors include: improving the sweat extraction and sweat sensing capabilities, improving the form factor of the wearable device for minimal discomfort and reliable measurements when worn, and understanding the clinical value of sweat analytes toward biomarker discovery. This review provides a comprehensive review of wearable sweat sensors and outlines state-of-the-art technologies and research that strive to bridge these gaps. The physiology of sweat, materials, biosensing mechanisms and advances, and approaches for sweat induction and sampling are introduced. Additionally, design considerations for the system-level development of wearable sweat sensing devices, spanning from strategies for prolonged sweat extraction to efficient powering of wearables, are discussed. Furthermore, the applications, data analytics, commercialization efforts, challenges, and prospects of wearable sweat sensors for precision medicine are discussed.

Differences in prophylactic performance across wound dressing types used to protect from device-related pressure ulcers caused by a continuous positive airway pressure mask

Prolonged use of continuous positive airway pressure masks, as often required for non-invasive ventilation, involves a risk for facial tissue breakdown due to the sustained deformations caused by tightening of the stiff mask surfaces to the head and the moist environment. The risk of developing mask-related facial injuries can be reduced through suitable cushioning materials placed at the skin-mask interfaces to spread the localised contact forces and disperse the surface and internal tissue stresses. Using an integrated experimental-computational approach, we compared the biomechanical protective performance of three popular foam-based wound dressings to that of a market-lead hydrocolloid dressing when applied to protect the facial skin under a mask. We measured the compressive stiffness properties of the four commercial dressing types in dry and moist conditions, and then fed those to an anatomically realistic finite element model of an adult male head, with an applied simulated mask. Through this process, we calculated the protective efficacy index of each dressing type, indicating the relative contribution of the specified dressing to alleviating facial soft tissue loads with respect to the no-dressing case. The foam-based dressings generally performed substantially better than the hydrocolloid, but foam dressings were also demonstrated to vary by their protective performance.

Transcriptomic profile comparison reveals conservation of ionocytes across multiple organs

Single-cell RNA sequencing has recently led to the identification of a flurry of rare, new cell types, such as the CFTR-high ionocytes in the airway epithelium. Ionocytes appear to be specifically responsible for fluid osmolarity and pH regulation. Similar cells exist in multiple other organs and have received various names, including intercalated cell in the kidney, mitochondria-rich cell in the inner ear, clear cell in the epididymis, and ionocyte in the salivary gland. Here, we compare the previously published transcriptomic profile of cells expressing FOXI1, the signature transcription factor expressed in airway ionocytes. Such FOXI1+ cells were found in datasets representing human and/or murine kidney, airway, epididymis, thymus, skin, inner ear, salivary gland, and prostate. This allowed us to assess the similarities between these cells and identify the core transcriptomic signature of this ionocyte 'family'. Our results demonstrate that, across all these organs, ionocytes maintain the expression of a characteristic set of genes, including FOXI1, KRT7, and ATP6V1B1. We conclude that the ionocyte signature defines a class of closely related cell types across multiple mammalian organs.

Effect of reflex and mechanical decreases in skin perfusion on thermal- and agonist-induced eccrine sweating in humans

In humans, skin blood flux (SkBF) and eccrine sweating are tightly coupled, suggesting common neural control and regulation. This study was designed to separate these two sympathetic nervous system end-organ responses via nonadrenergic SkBF-decreasing mechanical perturbations during heightened sudomotor drive. We induced sweating physiologically via whole body heat stress using a high-density tube-lined suit (protocol 1; 2 women, 4 men), and pharmacologically via forearm intradermal microdialysis of two steady-state doses of a cholinergic agonist, pilocarpine (protocol 2; 4 women, 3 men). During sweating induction, we decreased SkBF via three mechanical perturbations: arm and leg dependency to engage the cutaneous venoarteriolar response (CVAR), limb venous occlusion to engage the CVAR and decrease perfusion pressure, and limb arterial occlusion to cause ischemia. In protocol 1, heat stress increased arm cutaneous vascular conductance and forearm sweat rate (capacitance hygrometry). During heat stress, despite decreases in SkBF during each of the acute (3 min) mechanical perturbations, eccrine sweat rate was unaffected. During heat stress with extended (10 min) ischemia, sweat rate decreased. In protocol 2, both pilocarpine doses (ED50 and EMAX) increased SkBF and sweat rate. Each mechanical perturbation resulted in decreased SkBF but minimal changes in eccrine sweat rate. Taken together, these data indicate that a wide range of acute decreases in SkBF do not appear to proportionally decrease either physiologically- or pharmacologically induced eccrine sweating in peripheral skin. This preservation of evaporative cooling despite acutely decreased SkBF could have consequential impacts for heat storage and balance during changes in body posture, limb position, or blood flow restrictive conditions.

TRPS1 Is Differentially Expressed in a Variety of Malignant and Benign Cutaneous Sweat Gland Neoplasms

Neoplasms of sweat glands and the breast may be morphologically and immunophenotypically similar. A recent study showed that TRPS1 staining is a highly sensitive and specific marker for breast carcinoma. In this study, we analyzed TRPS1 expression in a spectrum of cutaneous sweat gland tumors. We stained five microcystic adnexal carcinomas (MACs), three eccrine adenocarcinomas, two syringoid eccrine carcinomas, four hidradenocarcinomas, six porocarcinomas, one eccrine carcinoma-NOS, 11 hidradenomas, nine poromas, seven cylindromas, three spiradenomas, and 10 syringomas with TRPS1 antibodies. All of the MACs and syringomas were negative. Every cylindroma and two of the three spiradenomas demonstrated intense staining in cells lining the ductular spaces, with negative to relatively weak expression in surrounding cells. Of the 16 remaining malignant entities, 13 were intermediate to high positive, one was low positive, and two were negative. From the 20 hidradenomas and poromas, intermediate to high positivity was revealed in 14 cases, low positivity in three cases, and negative staining in three cases. Our study demonstrates a very high (86%) expression of TRPS1 in malignant and benign adnexal tumors that are mainly composed of islands or nodules with polygonal cells, e.g., hidradenomas. On the other hand, tumors with small ducts or strands of cells, such as MACs, appear to be completely negative. This differential staining among types of sweat gland tumors may represent either differential cells of origin or divergent differentiation and has the potential to be used as a diagnostic tool in the future.

Differential modularity of the mammalian Engrailed 1 enhancer network directs sweat gland development

Enhancers are context-specific regulators of expression that drive biological complexity and variation through the redeployment of conserved genes. An example of this is the enhancer-mediated control of Engrailed 1 (EN1), a pleiotropic gene whose expression is required for the formation of mammalian eccrine sweat glands. We previously identified the En1 candidate enhancer (ECE) 18 cis-regulatory element that has been highly and repeatedly derived on the human lineage to potentiate ectodermal EN1 and induce our species' uniquely high eccrine gland density. Intriguingly, ECE18 quantitative activity is negligible outside of primates and ECE18 is not required for En1 regulation and eccrine gland formation in mice, raising the possibility that distinct enhancers have evolved to modulate the same trait. Here we report the identification of the ECE20 enhancer and show it has conserved functionality in mouse and human developing skin ectoderm. Unlike ECE18, knock-out of ECE20 in mice reduces ectodermal En1 and eccrine gland number. Notably, we find ECE20, but not ECE18, is also required for En1 expression in the embryonic mouse brain, demonstrating that ECE20 is a pleiotropic En1 enhancer. Finally, that ECE18 deletion does not potentiate the eccrine phenotype of ECE20 knock-out mice supports the secondary incorporation of ECE18 into the regulation of this trait in primates. Our findings reveal that the mammalian En1 regulatory machinery diversified to incorporate both shared and lineage-restricted enhancers to regulate the same phenotype, and also have implications for understanding the forces that shape the robustness and evolvability of developmental traits.

The human protein atlas-Integrated omics for single cell mapping of the human proteome

Studying the spatial distribution of proteins provides the basis for understanding the biology, molecular repertoire, and architecture of every human cell. The Human Protein Atlas (HPA) has grown into one of the world's largest biological databases, and in the most recent version, a major update of the structure of the database was performed. The data has now been organized into 10 different comprehensive sections, each summarizing different aspects of the human proteome and the protein-coding genes. In particular, large datasets with information on the single cell type level have been integrated, refining the tissue and cell type specificity and detailing the expression in cell states with an increased resolution. The multi-modal data constitute an important resource for both basic and translational science, and hold promise for integration with novel emerging technologies at the protein and RNA level.

Hyperhidrosis: A Central Nervous Dysfunction of Sweat Secretion

Hyperhidrosis (HH) is a central nervous dysfunction characterized by abnormally increased sweating due to a central dysregulation of sweat secretion. HH significantly affects the quality of life of patients in their private, social and professional environments. Physiologically, sweating is a mechanism that regulates body temperature, but it may also be triggered by emotional or gustatory stimuli. There are two main types of sweat glands: eccrine and apocrine glands. The central nervous system controls sweat secretion through the release of neurotransmitters into the autonomous nervous system (ANS) that activate the sweat glands. The hypothalamus has two separate neuronal pathways, one for thermoregulation and one for emotions. HH may thus be due to either a neuronal dysfunction of ANS regulation leading to a hyperactivity of the sympathetic nervous system, or to abnormal central processing of emotions. Crucially, there is no dysfunction of the sweat glands themselves. Various pathogenic mechanisms have been proposed to be involved in pathological sweat secretion in HH, ranging from structural changes within the ANS to increased expression of aquaporin 5 and upregulation of activin A receptor type 1 in eccrine sweat glands. Although a genetic predisposition has been demonstrated, it remains unclear exactly which genes are involved. To identify new, potential therapeutic targets and to improve treatment options, a good understanding of the signaling pathways involved, the underlying mechanisms, and the genetic components is essential. In this review we discuss the various aspects of sweat physiology and function that are necessary to explain pathological sweating. Our aim is to raise awareness of the complexity of HH to promote a better understanding of the disorder.

Differential antigen expression between human apocrine sweat glands and eccrine sweat glands

Bromhidrosis has a great negative impact on personal occupation and social psychology. It is not yet clear whether bromhidrosis is caused by apocrine sweat glands or the co-action of apocrine sweat glands and eccrine sweat glands. To distinguish between apocrine sweat glands and eccrine sweat glands, specific antigen markers for apocrine sweat glands and eccrine sweat glands must be found first. In the study, we detected the expression of K7, K18, K19, Na+-K+-2Cl- cotransporter 1 (NKCC1), carbonic anhydrase II (CAII), Forkhead transcription factor a1 (Foxa1), homeobox transcription factor engrailed homeobox1 (En1), gross cystic disease fluid protein-15 (GCDFP-15), mucin-1 (MUC-1), cluster of differentiation 15 (CD15) and apolipoprotein (APOD) in eccrine sweat glands and apocrine sweat glands by immunofluorescence staining. The results showed that K7, K18, K19, Foxa1, GCDFP-15 and MUC-1 were expressed in both apocrine and eccrine sweat glands, CD15 and APOD were only expressed in apocrine sweat glands, and CAII, NKCC1 and En1 were only expressed in eccrine sweat glands. We conclude that CD15 and APOD can serve as specific markers for apocrine sweat glands, while CAII, NKCC1 and En1 can serve as specific markers for eccrine sweat glands to differentiate the two sweat glands.

Impacts of Skin Eccrine Glands on the Measured Values of Transepidermal Water Loss

Transepidermal water loss (TEWL) is widely used to assess and quantify skin insensible water loss to assess skin's barrier function integrity. Low TEWL values are normally indicative of intact skin and a healthy functional barrier, whereas an increased TEWL reveals a disturbed or disrupted skin barrier. Because most skin sites at which these measurements are made have eccrine glands present, the contribution of the sweat gland activity to these measurements is variable and, in most cases, unknown. The separation between the contribution of water loss that is reflective of the skin barrier integrity versus that contributed via eccrine activation is not easy and is made more difficult since both components increase with increasing skin and environmental temperature. Endogenous factors that impact eccrine sweat gland activity include sympathetic nervous system activity, emotional stress, physical activity, eccrine gland density, and age. Exogenous factors that impact eccrine gland activity include ambient temperature and humidity and the climate where one resides. The aforementioned variables impact eccrine gland activity positively or negatively and therefore alter TEWL values accordingly. Although it may be theoretically possible to control all these factors, the difficulty in doing so results in only a few being controlled during most TEWL measurements. Such confounding processes may have impacted historical TEWL reference ranges and values previously reported. Thus, the impact of eccrine activation on standardly measured TEWL values is at this juncture unclear and may be a component contributing to some reported variability in TEWL values. To help clarify the issues, a literature review was conducted to investigate and summarize relevant prior research efforts and outcomes with respect to ways to consider eccrine activity in TEWL measurements and estimate the contribution of eccrine gland activity to TEWL values. Online databases such as Excerpta Medica Database (EMBASE), Public/Publisher Medline (PubMed), Elton B. Stephans Company (EBSCO), Google Scholar, and Wiley Online Library were searched with "transepidermal water loss" or "TEWL" in the title combined with "eccrine glands" or "sweat" anywhere in the text. The present findings indicate a multiplicity of biological and environmental variables impacting eccrine gland activity and thereby potentially affecting measured TEWL values. Even if laboratory conditions adhere to various guidelines and recommendations, it is not yet possible to separate the eccrine activation component from the parameter of true interest in the assessment of the skin's physiological barrier function except for full gland deactivation. The amount that such eccrine gland activation impacts the measured value of TEWL is generally not determined using currently available methods and the only sure way to eliminate a confounding effect is to inactivate the glands during such TEWL measurements. Because such eccrine gland deactivating approach is not usually desirable or even possible, other approaches would be recommended. One would be the development of a measuring device that could distinguish between the component of TEWL that is associated with the skin barrier function and the other that is attributable to sweat gland activation. Further research and development along these lines appear warranted.

Biofabrication of Human Skin with Its Appendages

Much effort has been made to generate human skin organ in the laboratory. Yet, the current models are limited due to the lack of many critical biological and structural features of the skin. Importantly, these in vitro models lack appendages and fail to recapitulate the whole human skin construction. Thus, engineering a human skin with the capacity to generate all components, including appendages, is a major challenge. This review intends to provide an update on the recent efforts underway to regenerate appendage-bearing skin organs based on scaffold-free and scaffold-based bioengineering approaches. Although the mouse skin equivalents containing hair follicles, sebaceous glands, and sweat glands have been established in vitro, there has been limited success in humans. A combination of biofabricated matrices and cell aggregates, such as organoids, can pave the way for generating skin substitutes with human-like biological, structural, and physical features. Accordingly, the formation of human skin organoids and reconstruction of vascularized skin equipped with immune cells prompt calls for more scientific research. The generation of appendage-bearing skin substitutes can be applied in practice for wound healing, hair restoration, and scar treatment.

Portable sauna stimulated-diaphoresis for the treatment of fluid-overload in peritoneal dialysis patients: A pilot study

Background

Fluid overload (FO) is a common problem in patients with peritoneal dialysis (PD), it is associated with adverse outcomes and may persist despite adjustements in PD therapy.

Objective

To evaluate the feasibility and safety of stimulated diaphoresis to reduce FO with the use of a portable sauna bath.

Methods

Open-label pilot study in patients on continuous ambulatory peritoneal dialysis (CAPD) and FO. The primary outcome was the treatment-related adverse events; secondary outcomes were changes in over-hydration (OH), body weight and blood pressure, FO symptoms, and sleep quality. Dialysis prescription and daily data were recorded. The intervention period consisted in a 30-min, 45°C sauna bath, daily for 10 days, using a portable sauna bath.

Results

Fifty-one out of 54 total sauna bath sessions were well tolerated. In three (5.5%) sessions adverse effects were reported: transient dizziness in two cases, and a second-degree skin burn in a patient with advanced diabetic neuropathy. OH (6.3 ± 1.2 L vs. 5.5 ± 1.3 L, p = 0.05), body weight (67.7 ± 11.4 vs. 66.8 ± 3.8 kg, p = 0.003), diastolic blood pressure (92 ± 13.5 vs. 83 ± 13.3 mmHg, P = 0.003) and PSQI score (7.3 ± 3.7 vs. 5.1 ± 3.2, p = 0.02) improved significantly between the control and intervention period, respectively.

Conclusions

Stimulated diaphoresis with a portable sauna bath could be a novel, safe, and effective alternative way to reduce FO in CAPD patients. Larger studies are needed to confirm our results.

Clinical trial registration

ClinicalTrials.gov, identifier: NCT03563898.

Controlling skin microbiome as a new bacteriotherapy for inflammatory skin diseases

The skin serves as the interface between the human body and the environment and interacts with the microbial community. The skin microbiota consists of microorganisms, such as bacteria, fungi, mites, and viruses, and they fluctuate depending on the microenvironment defined by anatomical location and physiological function. The balance of interactions between the host and microbiota plays a pivotal role in the orchestration of skin homeostasis; however, the disturbance of the balance due to an alteration in the microbial communities, namely, dysbiosis, leads to various skin disorders. Recent developments in sequencing technology have provided new insights into the structure and function of skin microbial communities. Based on high-throughput sequencing analysis, a growing body of evidence indicates that a new treatment using live bacteria, termed bacteriotherapy, is a feasible therapeutic option for cutaneous diseases caused by dysbiosis. In particular, the administration of specific bacterial strains has been investigated as an exclusionary treatment strategy against pathogens associated with chronic skin disorders, whereas the safety, efficacy, and sustainability of this therapeutic approach using isolated live bacteria need to be further explored. In this review, we summarize our current understanding of the skin microbiota, as well as therapeutic strategies using characterized strains of live bacteria for skin inflammatory diseases. The ecosystem formed by interactions between the host and skin microbial consortium is still largely unexplored; however, advances in our understanding of the function of the skin microbiota at the strain level will lead to the development of new therapeutic methods.

Differential distribution and genetic determination of eccrine sweat glands and hair follicles in the volar skin of C57BL/6 mice and SD rats

BACKGROUND

Eccrine sweat glands (ESGs) and hair follicles (HFs) are the prominent skin appendages regulating human body temperature. C57BL/6 mice and Sprague-Dawley (SD) rats are the most commonly used model animals for studying ESGs and HFs. Previous studies have shown the distribution of ESGs and HFs in volar hindfeet of C57BL/6 mice, but there are few or no reports on the distribution of ESGs and HFs in volar forefeet of C57BL/6 mice and volar feet of SD rats. Here, we investigated the differential distribution and genetic determination of ESGs and HFs in the volar skin of C57BL/6 mice and SD rats through gross observation, iodine-starch sweat test, double staining with Nile Blue A and Oil Red O, hematoxylin and eosin (HE) staining, double immunofluorescence staining of LIM Homeobox 2 (LHX2)/Na⁺-K⁺-ATPase α1(NKA) or LHX2/Na⁺-K⁺-2Cl^－ cotransporter 1 (NKCC1), and qRT-PCR detection of ESG-related gene Engrailed 1 (En1) and HF-related gene LHX2.

RESULTS

The results showed ESGs but no HFs in the footpads of C57BL/6 mice and SD rats, both ESGs and HFs in the inter-footpads (IFPs) of C57BL/6 mice, and neither ESGs nor HFs in the IFPs of SD rats. The relative quantitative change in En1 was consistent with the differential distribution of ESGs, and the relative quantitative change of LHX2 was consistent with the differential distribution of HFs.

CONCLUSION

C57BL/6 mice and SD rats had their own characteristics in the distribution of ESGs and HFs in the volar skin, and researchers should choose mice or rats, and even forefeet or hindfeet as their research object according to different purposes. The study provides a basis for selection of optimal animal models to study development, wound healing and regeneration of skin appendages.

Foxa1 mediates eccrine sweat gland development through transcriptional regulation of Na-K-ATPase expression

Eccrine sweat glands (ESGs) perform critical functions in temperature regulation in humans. Foxa1 plays an important role in ESG maturation and sweat secretion. Its molecular mechanism, however, remains unknown. This study investigated the expression of Foxa1 and Na-K-ATPase (NKA) in rat footpads at different development stages using immunofluorescence staining, qRT-PCR, and immunoblotting. Also, bioinformatics analysis and Foxa1 overexpression and silencing were employed to evaluate Foxa1 regulation of NKA. The results demonstrated that Foxa1 was consistently expressed during the late stages of ESGs and had a significant role in secretory coil maturation during sweat secretion. Furthermore, the mRNA abundance and protein expression of NKA had similar accumulation trends to those of Foxa1, confirming their underlying connections. Bioinformatics analysis revealed that Foxa1 may interact with these two proteins via binding to conserved motifs in their promoter regions. Foxa1 gain-of-function and loss-of-function experiments in Foxa1-modified cells demonstrated that the activities of NKA were dependent on the presence of Foxa1. Collectively, these data provided evidence that Foxa1 may influence ESG development through transcriptional regulation of NKA expression.

Corin Deficiency Alters Adipose Tissue Phenotype and Impairs Thermogenesis in Mice

Atrial natriuretic peptide (ANP) is a key regulator in body fluid balance and cardiovascular biology. In addition to its role in enhancing natriuresis and vasodilation, ANP increases lipolysis and thermogenesis in adipose tissue. Corin is a protease responsible for ANP activation. It remains unknown if corin has a role in regulating adipose tissue function. Here, we examined adipose tissue morphology and function in corin knockout (KO) mice. We observed increased weights and cell sizes in white adipose tissue (WAT), decreased levels of uncoupling protein 1 (Ucp1), a brown adipocyte marker in WAT and brown adipose tissue (BAT), and suppressed thermogenic gene expression in BAT from corin KO mice. At regular room temperature, corin KO and wild-type mice had similar metabolic rates. Upon cold exposure at 4 °C, corin KO mice exhibited impaired thermogenic responses and developed hypothermia. In BAT from corin KO mice, the signaling pathway of p38 mitogen-activated protein kinase, peroxisome proliferator-activated receptor c coactivator 1a, and Ucp1 was impaired. In cell culture, ANP treatment increased Ucp1 expression in BAT-derived adipocytes from corin KO mice. These data indicate that corin mediated-ANP activation is an important hormonal mechanism in regulating adipose tissue function and body temperature upon cold exposure in mice.

The genetic history of Mayotte and Madagascar cattle breeds mirrors the complex pattern of human exchanges in Western Indian Ocean

Despite their central economic and cultural role, the origin of cattle populations living in Indian Ocean islands still remains poorly documented. Here, we unravel the demographic and adaptive histories of the extant Zebus from the Mayotte and Madagascar islands using high-density SNP genotyping data. We found that these populations are very closely related and both display a predominant indicine ancestry. They diverged in the 16th century at the arrival of European people who transformed the trade network in the area. Their common ancestral cattle population originates from an admixture between an admixed African zebu population and an Indian zebu that occurred around the 12th century at the time of the earliest contacts between human African populations of the Swahili corridor and Austronesian people from Southeast Asia in Comoros and Madagascar. A steep increase in the estimated population sizes from the beginning of the 16th to the 17th century coincides with the expansion of the cattle trade. By carrying out genome scans for recent selection in the two cattle populations from Mayotte and Madagascar, we identified sets of candidate genes involved in biological functions (cancer, skin structure, and UV-protection, nervous system and behavior, organ development, metabolism, and immune response) broadly representative of the physiological adaptation to tropical conditions. Overall, the origin of the cattle populations from Western Indian Ocean islands mirrors the complex history of human migrations and trade in this area.

A novel cell line from human eccrine sweat gland duct cells for investigating sweating physiology

OBJECTIVE

Human eccrine sweat glands represent vital components of the skin involved in regulating body temperature. Especially the eccrine duct, which opens directly into the skin surface and releases the aqueous sweat, constitutes the first contact point with topically applied substances. For scientific investigations and to understand the underlying sweating mechanism on a cellular level defined cellular material is beneficial. We, therefore, strived to generate a cell line derived from human eccrine sweat gland duct cells for identifying new mechanisms in sweating control, as such a standardize cell line is currently lacking.

MATERIAL AND METHODS

Isolated primary human eccrine sweat gland duct cells were transduced with simian virus 40 large T antigen (SV40T) by lentiviral transduction. Successfully SV40T-transduced clones were selected by single cell cloning with one clone, named 1D10, being particularly described in this work.

RESULTS

In performed cellular investigations, SV40T-transduced duct-derived cells exhibited an extended lifespan with stable population doubling times suggesting its immortality. Besides, 1D10 clonal cell culture demonstrated similarities with parental, primary duct cells regarding gene expression of selected sweat gland-related markers. When combined with primary coil cells in a hanging drop co-culture, those transduced duct-derived cells showed some duct cell-like features. Further, a certain degree of cellular communication and a specific reaction towards substance application was observed.

CONCLUSION

Generated and herein described cell line derived from isolated human eccrine sweat gland duct cells is, based on the presented scientific findings, considered as immortal. Besides, this cell line shows some similarity with primary duct cells, although alterations from native glands were detected, among which is loss of expression of CFTR. Provided some further investigations, presented SV40T-transduced duct-cell derived cell line seems a suited surrogate of primary eccrine duct cells.

Pathophysiological aspects of the thick ascending limb and novel genetic defects: HELIX syndrome and transient antenatal Bartter syndrome

The thick ascending limb plays a central role in human kidney physiology, participating in sodium reabsorption, urine concentrating mechanisms, calcium and magnesium homeostasis, bicarbonate and ammonium homeostasis, and uromodulin synthesis. This review aims to illustrate the importance of these roles from a pathophysiological point of view by describing the interactions of the key proteins of this segment and by discussing how recently identified and long-known hereditary diseases affect this segment. The descriptions of two recently described salt-losing tubulopathies, transient antenatal Bartter syndrome and HELIX syndrome, which are caused by mutations in MAGED2 and CLDN10 genes, respectively, highlight the role of new players in the modulation of sodium reabsorption the thick ascending limb.

Comprehensive Review on Wearable Sweat-Glucose Sensors for Continuous Glucose Monitoring

The incidence of diabetes is increasing at an alarming rate, and regular glucose monitoring is critical in order to manage diabetes. Currently, glucose in the body is measured by an invasive method of blood sugar testing. Blood glucose (BG) monitoring devices measure the amount of sugar in a small sample of blood, usually drawn from pricking the fingertip, and placed on a disposable test strip. Therefore, there is a need for non-invasive continuous glucose monitoring, which is possible using a sweat sensor-based approach. As sweat sensors have garnered much interest in recent years, this study attempts to summarize recent developments in non-invasive continuous glucose monitoring using sweat sensors based on different approaches with an emphasis on the devices that can potentially be integrated into a wearable platform. Numerous research entities have been developing wearable sensors for continuous blood glucose monitoring, however, there are no commercially viable, non-invasive glucose monitors on the market at the moment. This review article provides the state-of-the-art in sweat glucose monitoring, particularly keeping in sight the prospect of its commercialization. The challenges relating to sweat collection, sweat sample degradation, person to person sweat amount variation, various detection methods, and their glucose detection sensitivity, and also the commercial viability are thoroughly covered.

Autophagy, not apoptosis, plays a role in lumen formation of eccrine gland organoids

Background:

Sweat secreted by eccrine sweat glands is transported to the skin surface through the lumen. The eccrine sweat gland develops from the initial solid bud to the final gland structure with a lumen, but how the lumen is formed and the mechanism of lumen formation have not yet been fully elucidated. This study aimed to investigate the mechanism of lumen formation of eccrine gland organoids (EGOs).

Methods:

Human eccrine sweat glands were isolated from the skin for tissue culture, and the primary cultured cells were collected and cultured in Matrigel for 14 days in vitro. EGOs at different development days were collected for hematoxylin and eosin (H&E) staining to observe morphological changes and for immunofluorescence staining of proliferation marker Ki67, cellular motility marker filamentous actin (F-actin), and autophagy marker LC3B. Western blotting was used to detect the expression of Ki67, F-actin, and LC3B. Moreover, apoptosis was detected using a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay kit, and the expression of poly (ADP-ribose) polymerase and Caspase-3 was detected by Western blot. In addition, 3-methyladenine (3MA) was used as an autophagy inhibitor to detect whether the formation of sweat glands can be effectively inhibited.

Results:

The results showed that a single gland cell proliferated rapidly and formed EGOs on day 4. The earliest lumen formation was observed on day 6. From day 8 to day 14, the rate of lumen formation in EGOs increased significantly. The immunofluorescence and Western blot analyses showed that the expression of Ki67 gradually decreased with the increase in days, while the F-actin expression level did not change. Notably, the expression of autophagy marker LC3B was detected in the interior cells of EGOs as the apoptosis signal of EGOs was negative. Compared with the control group, the autophagy inhibitor 3MA can effectively limit the formation rate of the lumen and reduce the inner diameter of EGOs.

Conclusion:

Using our model of eccrine gland 3D-reconstruction in Matrigel, we determined that autophagy rather than apoptosis plays a role in the lumen formation of EGOs.

Establishment and characterization of immortalized sweat gland myoepithelial cells

Sweat glands play an important role in thermoregulation via sweating, and protect human vitals. The reduction in sweating may increase the incidence of hyperthermia. Myoepithelial cells in sweat glands exhibit stemness characteristics and play a major role in sweat gland homeostasis and sweating processes. Previously, we successfully passaged primary myoepithelial cells in spheroid culture systems; however, they could not be maintained for long under in vitro conditions. No myoepithelial cell line has been established to date. In this study, we transduced two immortalizing genes into primary myoepithelial cells and developed a myoepithelial cell line. When compared with primary sweat gland cells, the immortalized myoepithelial cells (designated "iEM") continued to form spheroids after the 4th passage and expressed α-smooth muscle actin and other proteins that characterize myoepithelial cells. Furthermore, treatment with small compounds targeting the Wnt signaling pathways induced differentiation of iEM cells into luminal cells. Thus, we successfully developed an immortalized myoepithelial cell line having differentiation potential. As animal models are not useful for studying human sweat glands, our cell line will be helpful for studying the mechanisms underlying the pathophysiology of sweating disorders.

3D-bioprinted microenvironments for sweat gland regeneration

The development of 3D bioprinting in recent years has provided new insights into the creation of in vitro microenvironments for promoting stem cell-based regeneration. Sweat glands (SGs) are mainly responsible for thermoregulation and are a highly differentiated organ with limited regenerative ability. Recent studies have focused on stem cell-based therapies as strategies for repairing SGs after deep dermal injury. In this review, we highlight the recent trend in 3D bioprinted native-like microenvironments and emphasize recent advances in functional SG regeneration using this technology. Furthermore, we discuss five possible regulatory mechanisms in terms of biochemical factors and structural and mechanical cues from 3D bioprinted microenvironments, as well as the most promising regulation from neighbor cells and the vascular microenvironment.

Exocrine gland structure-function relationships

Fluid secretion by exocrine glandular organs is essential to the survival of mammals. Each glandular unit within the body is uniquely organized to carry out its own specific functions, with failure to establish these specialized structures resulting in impaired organ function. Here, we review glandular organs in terms of shared and divergent architecture. We first describe the structural organization of the diverse glandular secretory units (the end-pieces) and their fluid transporting systems (the ducts) within the mammalian system, focusing on how tissue architecture corresponds to functional output. We then highlight how defects in development of end-piece and ductal architecture impacts secretory function. Finally, we discuss how knowledge of exocrine gland structure-function relationships can be applied to the development of new diagnostics, regenerative approaches and tissue regeneration.

Whole-Genome comparative analysis reveals genetic mechanisms of disease resistance and heat tolerance of tropical Bos indicus cattle breeds

The Bos indicus cattle breeds have been naturally selected over thousands of years for disease resistance and thermo-tolerance. However, a genetic mechanism of these specific inherited characteristics needs to be discovered. Hence, in this study, the whole-genome comparative analysis of Bos indicus cattle breeds of Kangayam, Tharparkar, Sahiwal, Red Sindhi, and Hariana of the Indian subcontinent was conducted. The genetic variants identification analysis revealed a total of 15,58,51,012 SNPs and 1,00,62,805 InDels in the mapped reads across all Bos indicus cattle breeds. The functional annotation of 17,252 genes that comprised both, SNPs and InDels, of high functional impact on proteins, has been carried out. The functional annotation results revealed the pathways that were involved in the innate immune response including toll-like receptors, a retinoic acid-inducible gene I like receptors, NOD-like receptors, Jak-STAT signaling pathways, and the non-synonymous variants in the candidate immune genes. Further, we also identified several pathways involved in heat shock response, hair and skin properties, oxidative stress response, osmotic stress response, thermal sweating, feed intake, metabolism, and the non-synonymous variants in the candidate thermo-tolerant genes. These pathways and genes were directly or indirectly contributing to the disease resistance and thermo-tolerance adaptations of Bos indicus cattle breeds.

Sweat Gland Organoids Originating from Reprogrammed Epidermal Keratinocytes Functionally Recapitulated Damaged Skin

Restoration of sweat glands (SwGs) represents a great issue in patients with extensive skin defects. Recent methods combining organoid technology with cell fate reprogramming hold promise for developing new regenerative methods for SwG regeneration. Here, a practical strategy for engineering functional human SwGs in vitro and in vivo is provided. First, by forced expression of the ectodysplasin-A in human epidermal keratinocytes (HEKs) combined with specific SwG culture medium, HEKs are efficiently converted into SwG cells (iSwGCs). The iSwGCs show typical morphology, gene expression pattern, and functions resembling human primary SwG cells. Second, by culturing the iSwGCs in a special 3D culturing system, SwG organoids (iSwGOs) that exhibit structural and biological features characteristic of native SwGs are obtained. Finally, these iSwGOs are successfully transplanted into a mouse skin damage model and they develop into fully functioning SwGs in vivo. Regeneration of functional SwG organoids from reprogrammed HEKs highlights the great translational potential for personalized SwG regeneration in patients with large skin defects.

Characterization of the Human Eccrine Sweat Proteome-A Focus on the Biological Variability of Individual Sweat Protein Profiles

The potential of eccrine sweat as a bio-fluid of interest for diagnosis and personalized therapy has not yet been fully evaluated, due to the lack of in-depth sweat characterization studies. Thanks to recent developments in omics, together with the availability of accredited sweat collection methods, the analysis of human sweat may now be envisioned as a standardized, non-invasive test for individualized monitoring and personalized medicine. Here, we characterized individual sweat samples, collected from 28 healthy adult volunteers under the most standardized sampling methodology, by applying optimized shotgun proteomics. The thorough characterization of the sweat proteome allowed the identification of 983 unique proteins from which 344 were identified across all samples. Annotation-wise, the study of the sweat proteome unveiled the over-representation of newly addressed actin dynamics, oxidative stress and proteasome-related functions, in addition to well-described proteolysis and anti-microbial immunity. The sweat proteome composition correlated with the inter-individual variability of sweat secretion parameters. In addition, both gender-exclusive proteins and gender-specific protein abundances were highlighted, despite the high similarity between human female and male sweat proteomes. In conclusion, standardized sample collection coupled with optimized shotgun proteomics significantly improved the depth of sweat proteome coverage, far beyond previous similar studies. The identified proteins were involved in many diverse biological processes and molecular functions, indicating the potential of this bio-fluid as a valuable biological matrix for further studies. Addressing sweat variability, our results prove the proteomic profiling of sweat to be a promising bio-fluid analysis for individualized, non-invasive monitoring and personalized medicine.

Cutaneous eccrine inflammation and necrosis: review of inflammatory disorders affecting the eccrine apparatus including new associations

Despite being frequently overlooked during the examination of histopathological sections, eccrine sweat glands can offer clues for diagnosing various skin conditions. They provide important functions and can lead to several diseases when inflamed or injured. This review article provides information regarding eccrine physiology as well as well-established and novel entities that occur in association with eccrine gland pathology.

A glycopyrronium bromide 1% cream for topical treatment of primary axillary hyperhidrosis: efficacy and safety results from a phase IIIa randomized controlled trial

BACKGROUND

Effective topical treatment options for patients with primary axillary hyperhidrosis (PAHH) are limited. A phase I trial showed promising results regarding the efficacy and safety of a topical cream containing glycopyrronium bromide (GPB).

OBJECTIVES

To assess the efficacy, safety and tolerability of a 4-week topical treatment of GPB 1% cream in patients with PAHH vs. placebo.

METHODS

In total, 171 patients (84 receiving placebo; 87 receiving GPB 1%) with PAHH were included in the 4-week, multicentre, randomized, double-blind, placebo-controlled phase IIIa part of the pivotal study. Sweat production was measured by gravimetry. Patients rated the impact of disease with the Hyperhidrosis Disease Severity Scale (HDSS) and Hyperhidrosis Quality of Life Index (HidroQoL© ).

RESULTS

Absolute change in sweat production from baseline to day 29 in logarithmic values was significantly larger in the GPB 1% group compared with the placebo group (P = 0·004). The improvement in HidroQoL exceeded the minimal clinically important difference of 4. The proportion of responders was twofold higher for sweat reduction (-197·08 mg GPB 1% vs. -83·49 mg placebo), HDSS (23% GPB 1% vs. 12% placebo) and HidroQoL (60% GPB 1% vs. 26% placebo). Treatment was safe: most treatment-emergent adverse effects were mild or moderate, and transient. Local tolerability was very good, with 9% of patients having only mild or moderate application-site reactions. The most reported adverse drug reaction was dry mouth (16%), an expected anticholinergic effect of the treatment.

CONCLUSIONS

GPB 1% cream may provide an effective new treatment option exhibiting a good safety profile for patients with PAHH. The long-term open-label part (phase IIIb) is ongoing.

What makes a hydrogel-based dressing advantageous for the prevention of medical device-related pressure ulcers

The synergistic influences of geometrical, mechanical and thermal mismatches between a skin‐contacting medical device and the skin may cause tissue stress concentrations and sharp temperature gradients, both of which contribute to the risk for medical device‐related pressure ulcers. In this work, we developed an innovative, integrated experimental bioengineering approach encompassing mechanical stiffness, friction and thermal property studies for testing the biomechanical suitability of a hydrogel‐based dressing in prophylaxis of injuries caused by devices. We characterised the viscoelastic stress relaxation of the dressing and determined its long‐term elastic modulus. We further measured the coefficient of friction of the hydrogel‐based dressing at dressing‐device and skin‐dressing interfaces, using a tilting‐table tribometer. Lastly, we measured the thermal conductivity of the dressing, using a heat‐flow meter and infrared thermography‐based method. All measurements considered dry and moist conditions, the latter simulating skin perspiration effects. Our results revealed that the long‐term stiffness and the thermal conductivity of the hydrogel‐based dressing matched the corresponding properties of human skin for both dry and moist conditions. The dressing further demonstrated a relatively high coefficient of friction at its skin‐facing and device‐facing aspects, indicating minimal frictional sliding. All these properties make the above dressing advantageous for prevention of device‐related injuries.