Noninvasive skin measurements to monitor chronic renal failure pathogenesis

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.

Advancements in non-invasive skin sampling: Clinical conditions characterization via the assessment of skin surface cytokine biomarkers

The skin is increasingly recognized as a biological active organ interacting with the immune system. Given that the epidermal skin layer actively releases various cytokines, non-invasive skin sampling methods could detect these cytokines, offering insights into clinical conditions. This study aims non-invasively measuring cytokine levels directly from the skin surface to characterize different inflammatory chronic disorders in the adult and elderly population: psoriasis, diabetes type 2, rosacea, chronic kidney disease (CKD) and aging. Cytokines IL-1β, IL-8 and IL-10 were sampled from healthy subjects and patients aged 18-80 using skin surface wash technique. A well with sterile phosphate-buffered saline solution was placed on the skin for 30 min, and the extracted solution was collected from the well for further cytokine levels analysis using ELISA assay. Results show distinct cytokine profiles in different pathological processes, healthy controls, affected and unaffected areas. Aging was associated with increased IL-1β, IL-8, and IL-10 levels in skin. In diabetes, IL-1β and IL-8 levels were elevated in lesional areas, while IL-10 levels were decreased in non-lesional skin. Psoriatic lesions showed elevated levels of IL-1β and IL-8. Rosacea patients had lower IL-10 levels in both lesional and non-lesional areas. CKD patients exhibited significantly lower IL-10 levels compared to healthy individuals. In conclusion, skin surface wash-derived cytokine profiles could serve as "alert biomarkers" for disease prediction, enabling early detection. Additionally, this method's cost-effectiveness allows pre-screening of molecules in clinical studies and holds potential as a tool for biomarkers and omics analysis, enhancing disorder characterization and disease management.

Disposable Potentiometric Sensory System for Skin Antioxidant Activity Evaluation

The skin is a natural barrier between the external and internal environment. Its protective functions and the relationship of its state with the state of health of the organism as a whole are very important. It is known that oxidant stress (OS) is a common indicator of health status. This paper describes a new sensory system for monitoring OS of the skin using antioxidant activity (AOA) as its criteria. The contact hybrid potentiometric method (CHPM) and new electrochemical measuring scheme were used. A new sensory system, including disposable modified screen-printed carbon and silver electrodes covered by membrane impregnated by mediator, was developed. Its informative ability was demonstrated in the evaluation of the impact of fasting, consumption of food and food enriched by vitamins (antioxidants) on skin AOA. This device consisting of a sensory system and potentiometric analyzer can be used in on-site and in situ formats.

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.

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

Background

The skin proteome contains valuable information on skin condition, but also on how skin may evolve in time and may respond to treatments. Despite the potential of measuring regulatory-, effector- and structural proteins in the skin for biomarker applications in clinical dermatology and skin care, convenient diagnostic tools are lacking. The aim of the present study was to develop a highly versatile and non-invasive diagnostic tool for multiplex measurements of protein biomarkers from the surface of skin.

Results

The Transdermal Analyses Patch (TAP) is a novel molecular diagnostic tool that has been developed to capture biomarkers directly from skin, which are quantitatively analyzed in spot-ELISA assays. Optimisation of protocols for TAP production and biomarker analyses makes TAP measurements highly specific and reproducible. In measurements of interleukin-1α (IL-1α), IL-1 receptor antagonist (IL-1RA) and human β-defensin (hBD-1) from healthy skin, TAP appears far more sensitive than skin lavage-based methods using ELISA. No side-effects were observed using TAP on human skin.

Conclusion

TAP is a practical and valuable new skin diagnostic tool for measuring protein-based biomarkers from skin, which is convenient to use for operators, with minimal burden for patients.

Impact of hemodialysis on exhaled volatile organic compounds in end-stage renal disease: a pilot study

Aim: To demonstrate the feasibility of nanomaterial-based sensors for identifying patterns of exhaled volatile organic compound of end-stage renal disease (ESRD) and study the impact of hemodialysis (HD) on these patterns. Patients & methods: Exhaled breath samples were collected from a group of 37 volunteers (26 ESRD HD patients; 11 healthy controls); a third of the samples were randomly blinded for determining the sensitivity/specificity of the method. Discriminant function analysis was used to build a model for discriminating ESRD patients and healthy controls (classification accuracy for blind samples: 80%), based on the signals of the nanomaterial sensors. Results & conclusion: The breath pattern of the ESRD patients approached the healthy pattern during the HD treatment, without reaching it completely. Gas chromatography/mass spectrometry identified four volatile organic compounds as potential ESRD biomarkers. Although this pilot study has yielded encouraging results, additional large-scale clinical studies are required to develop a fast, noninvasive breath test for monitoring HD adequacy in real time.

Original submitted 23 September 2012; Revised submitted 26 February 2013

Advanced kidney failure and hyperuricemia

Metabolic end products accumulate in kidney failure, including uric acid (UA), a terminal product of purine catabolism. Hyperuricemia (HUA) can cause gout and has been increasingly linked with cardiovascular (CV) morbidity and mortality, outcomes that are highly prevalent in patients with kidney disease. Serum UA levels rise as glomerular filtration declines, whereas the frequency of gouty attacks declines and the incidence of CV death rises precipitously. Herein, we review the kinetics of UA metabolism in CKD and dialysis and discuss the possible mechanisms of gout mitigation in kidney failure and the potential contribution of hyperuricemic milieu to CV outcomes in patients with kidney disease.

Sericin cream reduces pruritus in hemodialysis patients: a randomized, double-blind, placebo-controlled experimental study

Background

Uremic pruritus (UP) is a significant complication in ESRD patients and substantially impairs their quality of life. UP is considered to be a skin manifestation of chronic inflammation. Because sericin can suppress the release of pro-inflammatory cytokines, the purpose of this study was to investigate the short-term safety and efficacy of sericin cream for treating UP in hemodialysis patients.

Methods

This study used a double-blind design to investigate the effects of random topical administration of sericin cream and cream base (placebo) on either the right or left extremities of hemodialysis patients for 6 weeks. Skin hydration, irritation and pigmentation were evaluated every 2 weeks using Skin Diagnostic SD27. The visual analog scale for itching was also evaluated every 2 weeks, and the Kidney Disease Quality of Life Short Form was performed on the day of each patient’s enrollment and after 6 weeks of treatment.

Results

Fifty dialysis patients were enrolled, 47 of which completed the study. The hydration of the skin of the patients’ extremities increased significantly after administration of sericin cream; significant differences were found between sericin treatment and control after 6 weeks of treatment (p = 0.041 for arms and p = 0.022 for legs, respectively). Moreover, a significant difference was also found in skin irritation between the two treatments (p = 0.013 for arms and p = 0.027 for legs, respectively). At the end of the study, the skin pigmentation level was significantly reduced on both the arms (p = 0.032) and legs (p = 0.021) of the sericin-treated side compared with the side treated with cream base. The mean itching score decreased significantly from moderate to severe at the time of enrollment to mild pruritus after 6 weeks of treatment (p = 0.002). A better quality of life was found in all domains tested although statistically significant differences before and after treatment was found only in the patients’ pain scores, the effect of kidney disease on daily life, sleep quality and symptoms or problems related to kidney disease.

Conclusions

We conclude that sericin cream has a high potential for reducing UP in hemodialysis patients.

The trial registration number of this study is ISRCTN16019033; its public title is “sericin cream reduces pruritus in hemodialysis patients”.