Development of TAP, a non-invasive test for qualitative and quantitative measurements of biomarkers from the skin surface

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.

Characterization of the internal working-life exposome using minimally and non-invasive sampling methods - a narrative review

During recent years, we are moving away from the 'one exposure, one disease'-approach in occupational settings and towards a more comprehensive approach, taking into account the totality of exposures during a life course by using an exposome approach. Taking an exposome approach however is accompanied by many challenges, one of which, for example, relates to the collection of biological samples. Methods used for sample collection in occupational exposome studies should ideally be minimally invasive, while at the same time sensitive, and enable meaningful repeated sampling in a large population and over a longer time period. This might be hampered in specific situations e.g., people working in remote areas, during pandemics or with flexible work hours. In these situations, using self-sampling techniques might offer a solution. Therefore, our aim was to identify existing self-sampling techniques and to evaluate the applicability of these techniques in an occupational exposome context by conducting a literature review. We here present an overview of current self-sampling methodologies used to characterize the internal exposome. In addition, the use of different biological matrices was evaluated and subdivided based on their level of invasiveness and applicability in an occupational exposome context. In conclusion, this review and the overview of self-sampling techniques presented herein can serve as a guide in the design of future (occupational) exposome studies while circumventing sample collection challenges associated with exposome studies.

Non-Invasive Assessment of Skin Surface Proteins of Psoriasis Vulgaris Patients in Response to Biological Therapy

Measurements of skin surface biomarkers have enormous value for the detailed assessment of skin conditions, both for clinical application and in skin care. The main goals of the current study were to assess whether expression patterns of skin surface hBD-1, hBD-2, IL-1α, CXCL-1, and CXCL-8, examples of proteins known to be involved in psoriasis pathology, are associated with disease severity and whether expression patterns of these proteins on the skin surface can be used to measure pharmacodynamic effects of biological therapy. In this observational study using transdermal analysis patch (TAP), levels of skin surface IL-1α, hBD-1, hBD-2, CXCL-1/2, and CXCL-8 of psoriasis vulgaris (PV) patients over biological therapy were assessed. The Psoriasis Area Severity Index (PASI) and local score for erythema, induration, and desquamation were determined from the exact same skin area as FibroTx TAP measurements. Thirty-seven adult PV patients were included, of which twenty-three were subjected to anti-TNF-α, seven to anti-IL-17A, and seven to anti-IL12/IL-23 therapy. Significantly higher levels of hBD-1, hBD-2, CXCL-1/2, and CXCL-8 were detected on lesional skin compared to the non-lesional skin of the PV patients. In contrast, lower levels of IL-1α were found in lesional skin compared to non-lesional skin. In addition, we observed that the biomarker expression levels correlate with disease severity. Further, we confirmed that changes in the expression levels of skin surface biomarkers during biological therapy correlate with treatment response. Biomarker expression patterns in response to treatment differed somewhat between treatment subtypes. We observed that, in the case of anti-TNF-α therapy, an increase after a steady decrease in the expression levels of CXCL-1/2 and CXCL-8 occurred before the change in clinical scores. Moreover, response kinetics of skin surface proteins differs between the applied therapies-hBD2 expression responds quickly to anti-IL-17A therapy, CXCL-1/2 to anti-IL-12/23, and levels of CXCL-8 are rapidly down-regulated by IL-17A and IL-12/23 therapy. Our findings confirm that the skin surface hBD-2, IL-1α, CXCL-1/2, and CXCL-8 are markers for the psoriasis severity. Further, data obtained during this study give the basis for the conclusion that skin surface proteins CXCL-1/2 and CXCL-8 may have value as therapeutic biomarkers, thus confirming that measuring the 'molecular root' of inflammation appears to have value in scoring disease severity on its own.

Field effect transistor based wearable biosensors for healthcare monitoring

The rapid advancement of wearable biosensors has revolutionized healthcare monitoring by screening in a non-invasive and continuous manner. Among various sensing techniques, field-effect transistor (FET)-based wearable biosensors attract increasing attention due to their advantages such as label-free detection, fast response, easy operation, and capability of integration. This review explores the innovative developments and applications of FET-based wearable biosensors for healthcare monitoring. Beginning with an introduction to the significance of wearable biosensors, the paper gives an overview of structural and operational principles of FETs, providing insights into their diverse classifications. Next, the paper discusses the fabrication methods, semiconductor surface modification techniques and gate surface functionalization strategies. This background lays the foundation for exploring specific FET-based biosensor designs, including enzyme, antibody and nanobody, aptamer, as well as ion-sensitive membrane sensors. Subsequently, the paper investigates the incorporation of FET-based biosensors in monitoring biomarkers present in physiological fluids such as sweat, tears, saliva, and skin interstitial fluid (ISF). Finally, we address challenges, technical issues, and opportunities related to FET-based biosensor applications. This comprehensive review underscores the transformative potential of FET-based wearable biosensors in healthcare monitoring. By offering a multidimensional perspective on device design, fabrication, functionalization and applications, this paper aims to serve as a valuable resource for researchers in the field of biosensing technology and personalized healthcare.

Epidermal Wearable Biosensors for Monitoring Biomarkers of Chronic Disease in Sweat

Biological information detection technology is mainly used for the detection of physiological and biochemical parameters closely related to human tissues and organ lesions, such as biomarkers. This technology has important value in the clinical diagnosis and treatment of chronic diseases in their early stages. Wearable biosensors can be integrated with the Internet of Things and Big Data to realize the detection, transmission, storage, and comprehensive analysis of human physiological and biochemical information. This technology has extremely wide applications and considerable market prospects in frontier fields including personal health monitoring, chronic disease diagnosis and management, and home medical care. In this review, we systematically summarized the sweat biomarkers, introduced the sweat extraction and collection methods, and discussed the application and development of epidermal wearable biosensors for monitoring biomarkers in sweat in preclinical research in recent years. In addition, the current challenges and development prospects in this field were discussed.

Assessment of soluble skin surface protein levels for monitoring psoriasis vulgaris in adult psoriasis patients using non-invasive transdermal analysis patch: A pilot study

To improve the care of patients with chronic inflammatory skin conditions, such as psoriasis, there is a need for diagnostic methods that can facilitate personalized medicine. This exploratory pilot study aimed to determine whether non-invasive measurements of inflammation-related proteins from psoriatic skin can be sampled using the FibroTx Transdermal Analysis Patch (TAP) to assess disease severity and monitor pharmacodynamic changes. Ten healthy volunteers and 44 psoriasis vulgaris patients were enrolled in the exploratory pilot study. Skin surface protein measurements for healthy and lesional skin were performed using TAP. Patients' scores of psoriasis activity and severity (PASI) were documented, and differences in the thickness of skin layers were determined using sonography. The study assessed the skin surface protein levels of psoriasis patients undergoing whole-body treatment with narrow-band UVB to evaluate whether the levels of the skin surface proteins IL-1α, IL-1RA CXCL-1/2, and hBD-1 were associated with the disease activity and severity measurements. Using TAP technology, it was observed that there were clear differences in levels of IL-1α, IL-1RA, CXCL-1/2, and hBD-1 between psoriasis lesional and non-lesional skin. In addition, a positive correlation between CXCL-1/2 and desquamation, and between CXCL-1/2 and SLEB thickness was observed. During UVB treatment, the TAP measurements revealed a clear reduction of IL-1RA, CXCL 1/2, and hBD-1 on lesional skin. Further, skin surface measurements of IL-1RA and CXCL-1/2 displayed a different profile than those achieved by visual scoring of local inflammation, thus indicating that measuring the 'molecular root' of inflammation appears to have value as an objective, non-invasive biomarker measurement for scoring disease severity.

Challenges in Noninvasive Skin Biomarker Measurements in Daily Practice: A Longitudinal Study on Skin Surface Protein Detection by the Transdermal Analysis Patch in Pediatric Psoriasis

INTRODUCTION

Skin surface proteins are potential biomarkers in psoriasis and can be measured noninvasively with the transdermal analysis patch (TAP). This study aimed to assess markers measured by TAP over time in daily clinical practice, explore their correlation with disease severity in pediatric psoriasis, and compare the TAP and tape stripping detection capability.

METHODS

In this prospective observational daily clinical practice study, pediatric psoriasis patients (aged >5 to <18 years) were followed during 1 year. At each visit, TAPs were applied to lesional (n = 2), peri-lesional (n = 2), and non-lesional (n = 1) sites. Post-lesional skin was sampled if all lesions on the arms, legs, or trunk cleared. Treatment and psoriasis severity data were collected. IL-1RA, hBD-2, IL-1α, IL-8, VEGF, CXCL-1/2, CCL-27, IL-23, hBD-1, IL-22, IL-17A, KLK-5, and IL-4 levels were quantified by spot-ELISA. For the statistical analysis, Wilcoxon signed rank tests, Mann-Whitney U tests, and Spearman correlations were used. Detection capability of the TAP was compared to tape stripping in a separate cohort of adult psoriasis patients.

RESULTS

32 patients (median age 15.0 years, median Psoriasis Area and Severity Index [PASI] 5.2) were followed for a mean of 11.3 (±3.4) months with a total of 104 visits. In lesional skin (n = 197), significantly higher IL-1RA, hBD-2, IL-8, VEGF, CXCL-1/2, IL-23, hBD-1, IL-22, CCL-27, and IL-17A levels were found compared to non-lesional skin (n = 104), while IL-1α was higher in non-lesional skin. Marker levels were highly variable over time and did not correlate with disease severity measured by PASI or SUM scores. Comparison of the TAP and tape strip detection capability in adult psoriasis patients (n = 10) showed that lesional hBD-2, IL1-α, IL-8, and VEGF and non-lesional IL-1RA, hBD-2, IL-8, and VEGF were more frequently detected in tape extracts than TAPs.

CONCLUSION

Due to the lack of correlation with clinical disease severity and the current detection capability of the markers measured by TAP in psoriasis, its use in regular practice is still a bridge too far.

Next-Generation Digital Biomarkers for Tuberculosis and Antibiotic Stewardship: Perspective on Novel Molecular Digital Biomarkers in Sweat, Saliva, and Exhaled Breath

The internet of health care things enables a remote connection between health care professionals and patients wearing smart biosensors. Wearable smart devices are potentially affordable, sensitive, specific, user-friendly, rapid, robust, lab-independent, and deliverable to the end user for point-of-care testing. The datasets derived from these devices are known as digital biomarkers. They represent a novel patient-centered approach to collecting longitudinal, context-derived health insights. Adding automated, analytical smartphone applications will enable their use in high-, middle-, and low-income countries. So far, digital biomarkers have been focused primarily on accelerometer data and heart rate due to well-established sensors originating from the consumer market. Novel emerging smart biosensors will detect biomarkers (or compounds) independent of a lab and noninvasively in sweat, saliva, and exhaled breath. These molecular digital biomarkers are a promising novel approach to reduce the burden from 2 major infectious diseases with urgent unmet needs: tuberculosis and infections with multidrug resistant pathogens. Active tuberculosis (aTbc) is one of the deadliest diseases from an infectious agent. However, a simple and reliable test for its detection is still missing. Furthermore, inappropriate antimicrobial use leads to the development of antimicrobial resistance, which is associated with high mortality and health care costs. From this perspective, we discuss the innovative approach of a noninvasive and lab-independent collection of novel biomarkers to detect aTbc, which at the same time may additionally serve as a scalable therapeutic drug monitoring approach for antibiotics. These molecular digital biomarkers are next-generation digital biomarkers and have the potential to shape the future of infectious diseases.

Skin Surface Protein Detection by Transdermal Analysis Patches in Pediatric Psoriasis

INTRODUCTION

Transdermal analysis patches (TAPs) noninvasively measure soluble proteins in the stratum corneum. Ultimately, such local protein profiles could benefit the search for biomarkers to improve personalized treatment in psoriasis. This study aimed to explore the patient friendliness and protein detection by TAP in pediatric psoriasis in daily clinical practice.

METHODS

In this observational study, TAPs measuring CXC chemokine ligand (CXCL)-1/2, CC chemokine ligand (CCL)-27, interleukin (IL)-1RA, IL-23, IL-1α, IL-8, IL-4, IL-22, IL-17A, vascular endothelial growth factor (VEGF), human beta-defensin (hBD)-2, hBD-1, and kallikrein-related peptidase (KLK)-5 were applied on lesional, peri-lesional, and non-lesional skin sites of psoriasis patients aged >5 to <18 years. Discomfort during TAP removal as an indicator for patient friendliness was assessed by visual analogue scale (VAS; range 0-10).

RESULTS

Thirty-two patients (median age 14.0 years) were included, of which 19 were treated with solely topical agents and 13 with systemic treatment. The median VAS of discomfort during TAP removal was 1.0 (interquartile range 1.0). Significantly higher levels in lesional versus non-lesional skin were found for IL-1RA, VEGF, CXCL-1/2, hBD-2, and IL-8, whereas lower levels were found for IL-1α. Skin surface proteins were measured in both treatment groups, with significant higher lesional levels of KLK-5, IL-1RA, hBD-2, IL-1α, IL-23, and CCL-27 in the systemic treatment group.

CONCLUSION

The TAP platform holds the potential for patient-friendly and noninvasive monitoring of skin-derived proteins in pediatric psoriasis patients in daily clinical practice.

Non-invasive assessment of soluble skin surface biomarkers in atopic dermatitis patients-Effect of treatment

BACKGROUND

Skin biomarkers are important tools for characterizing specific disease processes in atopic dermatitis (AD) patients and can be used for monitoring and potentially predicting treatment response. Recent developments of minimally invasive skin sampling methods have made sampling easier and less inconvenient for patients. The objective of this study was to evaluate the non-invasive patch technique developed by FibroTx for skin biomarker analysis.

MATERIALS AND METHODS

Ten adult patients with AD were included in the study and treated with topical corticosteroid (diprosone 0.05%) for 2 weeks. Skin surface biomarkers were assessed in three lesional and non-lesional sites before and during treatment using the FibroTx Patch method. Skin tape strips were also collected from the subjects for comparison.

RESULTS

The results showed expression of IL-1 cytokine family members, chemokines, and defensins on lesional and non-lesional skin. Several of these markers were strongly reduced by topical treatment. The biomarker expression in skin surface eluates correlated strongly with those seen in skin tape strips from the same subjects.

CONCLUSION

These data further support the usefulness of non-invasive sampling methods for assessing inflammatory processes in AD skin and demonstrate that the patch sampling method is a good alternative to skin tape strips.

Non-invasive Drug Monitoring of β-Lactam Antibiotics Using Sweat Analysis-A Pilot Study

Background: Antimicrobial resistance is a major challenge in treating infectious diseases. Therapeutic drug monitoring (TDM) can optimize and personalize antibiotic treatment. Previously, antibiotic concentrations in tissues were extrapolated from skin blister studies, but sweat analyses for TDM have not been conducted. Objective: To investigate the potential of sweat analysis as a non-invasive, rapid, and potential bedside TDM method. Methods: We analyzed sweat and blood samples from 13 in-house patients treated with intravenous cefepime, imipenem, or flucloxacillin. For cefepime treatment, full pharmacokinetic sampling was performed (five subsequent sweat samples every 2 h) using ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry. The ClinicalTrials.gov registration number is NCT03678142. Results: In this study, we demonstrated for the first time that flucloxacillin, imipenem, and cefepime are detectable in sweat. Antibiotic concentration changes over time demonstrated comparable (age-adjusted) dynamics in the blood and sweat of patients treated with cefepime. Patients treated with standard flucloxacillin dosage showed the highest mean antibiotic concentration in sweat. Conclusions: Our results provide a proof-of-concept that sweat analysis could potentially serve as a non-invasive, rapid, and reliable method to measure antibiotic concentration and as a surrogate marker for tissue penetration. If combined with smart biosensors, sweat analysis may potentially serve as the first lab-independent, non-invasive antibiotic TDM method.

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.

Extraction and biomolecular analysis of dermal interstitial fluid collected with hollow microneedles

Dermal interstitial fluid (ISF) is an underutilized information-rich biofluid potentially useful in health status monitoring applications whose contents remain challenging to characterize. Here, we present a facile microneedle approach for dermal ISF extraction with minimal pain and no blistering for human subjects and rats. Extracted ISF volumes were sufficient for determining transcriptome, and proteome signatures. We noted similar profiles in ISF, serum, and plasma samples, suggesting that ISF can be a proxy for direct blood sampling. Dynamic changes in RNA-seq were recorded in ISF from induced hypoxia conditions. Finally, we report the first isolation and characterization, to our knowledge, of exosomes from dermal ISF. The ISF exosome concentration is 12-13 times more enriched when compared to plasma and serum and represents a previously unexplored biofluid for exosome isolation. This minimally invasive extraction approach can enable mechanistic studies of ISF and demonstrates the potential of ISF for real-time health monitoring applications.

Expression of cutaneous immunity markers during infant skin maturation

BACKGROUND/OBJECTIVES

Infant skin undergoes a maturation process during the early years of life. Little is known about the skin's innate immunity. We investigated the dynamics of innate immunity markers collected from the surface of infant skin during the first 36 months of life.

METHODS

A total of 117 healthy infants aged 3-36 months participated in the study. We extracted human beta defensin-1 and interleukin 1 alpha and its receptor antagonist using transdermal analysis patches from the skin surface of the posterior lower leg area. The extracts were analyzed using a spot enzyme-linked immunosorbent assay.

RESULTS

Skin surface human beta defensin-1 levels were higher early in life and decreased with infant age. The ratio of interleukin 1 alpha receptor antagonist to interleukin 1 alpha did not change significantly with age but showed a distinct difference between sexes, with female infants having higher values than male infants.

CONCLUSION

As is the case with skin structure and functional properties, cutaneous innate immunity also appears to undergo a maturation period during infancy, with innate immunity slowly declining as adaptive immunity takes over. Sex differences in immune markers may explain sex-dependent susceptibilities to infection.

ELIPatch, a thumbnail-size patch with immunospot array for multiplexed protein detection from human skin surface

Proteins secreted by skin have great potential as biomarkers for interpreting skin conditions. However, inconvenience in handling and bulky size of existing methods are existing limitations. Here, we describe a thumb-nail sized patch with the array of microdisks which captures multiple proteins from the skin surface. Microdisks with antibody on the surface enable multiplexed immunoassay. By self-assembly, microdisks are placed into 2-dimensional arrays on adhesive tape. The proposed Enzyme-Linked Immunospot array on a Patch shows sufficient sensitivity for IL-1α, IL1RA, IL-17A, IFN-g, and TNF-α, while IL-6 and IL-1β are non-detectable in some cases. As demonstrations, we quantified cytokines from different skin regions and volunteers in a high-spatial-resolution.

Use of intralesional blood to determine diffusible biomarkers from skin lesions

BACKGROUND

Biomarkers provide beneficial information to make diagnoses and monitor the progression of many skin diseases. However, biomarkers produced by skin lesion may be too low at concentration to be detected in the systemic circulation.

OBJECTIVE

To address whether intralesional blood (ILB) is advantageous to detect skin-derived biomarkers over circulation blood (CB) of patients with skin diseases.

METHODS

ILB was collected as overflowing blood when a small incision was made in lesions of patients with mastocytoma and psoriasis. Concentrations of histamine and Human β-Defensin 2 were determined by ELISA. IL-8 was measured using a cytometric beads array (CBA) kit. IL-8 levels in psoriatic lesions were assessed by immunohistochemical staining and quantitative (q) RT-PCR. MicroRNA levels were measured using qRT-PCR.

RESULTS

Plasma histamine levels were increased in ILB of mastocytoma compared with those in CB. Patients with psoriasis showed increased levels of IL-8, β-Defensin 2 in ILB as compared to those in CB. IL-8 levels in ILB correlated with local PASI scores and therefore reversed to those in CB after attenuation of psoriasis with treatment. Furthermore, ILB in psoriasis patients showed increased miR-203, which was highly expressed in psoriatic epidermis.

CONCLUSION

ILB contains disease-specific biomarkers at higher concentrations than those in CB, and may be useful for diagnosis and monitoring the progression of skin diseases. Thus, this study illustrates the versatility of ILB with an easy accessibility of biomarkers of chemicals, proteins as well as nucleic acids for a myriad of diseases including inflammatory dermatoses and cancers.

Effects of blue light on inflammation and skin barrier recovery following acute perturbation. Pilot study results in healthy human subjects

BACKGROUND/PURPOSE

While growing evidence supports the therapeutic effect of 453 nm blue light in chronic inflammatory skin diseases, data on its effects on acutely perturbed human skin are scarce. In this study, we investigated the impact of 453 nm narrow-band LED light on healthy skin following acute perturbation.

METHODS

Tape stripping and histamine iontophoresis were performed on the forearm of 22 healthy volunteers on 2 consecutive weeks. In 1 week, challenges were followed by irradiation for 30 minutes. In the other week (control), no light was administered. Reactions were evaluated up to 72 hours thereafter by transepidermal water loss (TEWL), diffuse reflectance spectroscopy, and skin surface biomarkers.

RESULTS

Skin barrier disruption resulted in upregulation of IL-1α at 24 hours after tape stripping (P = .029). In contrast, irradiation abrogated this effect (P > .05). Irradiation also resulted in higher TEWL at 24 hours and in higher b* value at 72 hours after tape stripping compared to the control (P = .034 and P = .018, respectively). At 30 minutes following histamine iontophoresis and irradiation, a trend toward a higher a* value compared to the control was observed (P = .051).

CONCLUSION

We provide the first in vivo evidence that blue light at 453 nm exerts biological effects on acutely perturbed healthy human skin.