Newborn and elderly skin: two fragile skins at higher risk of pressure injury

Body mass index and pressure injuries risk in hospitalized adult patients: A dose-response analysis

BACKGROUND

The association between underweight and pressure injuries (PIs) has been established in several studies. However, there is a lack of well-designed research investigating the connection between overweight and obesity with these injuries.

OBJECTIVE

This meta-analysis aims to investigate the dose-response relationship between body mass index (BMI) and the risk of PIs in adult hospitalized patients.

METHODS

PubMed, Web of Science, and MEDLINE Databases were searched from inception to May 2024. Observational articles with at least three BMI categories were included in the study. BMI was defined as underweight, normal weight, overweight, and morbid obesity for the meta-analysis. The non-linear relationship between BMI and the risk of PIs in hospitalized adults was investigated using restricted cubic spline models. Fractional polynomial modeling was used.

RESULTS

Eleven articles reporting at least 3 categories of BMI met the inclusion criteria, including 31,389 participants. Compared to patients with normal weight, those with underweight, obesity, and morbid obesity exhibited an increased risk of PIs, with odds ratios of 1.70 (95%CI:1.50-1.91), 1.12 (95%CI:1.02-1.24), 1.70 (95%CI:1.13-2.55), respectively. A J-shaped dose-response model was established for the relationship between PI risk and BMI (Pnon-linearity < 0.001, Plinearity = 0.745).

CONCLUSION

The J-shaped dose-response pattern revealed that underweight, obesity and morbid obesity heightened the risk of PIs in hospitalized adults. Lower and higher BMI values may signify an increased risk for PIs, particularly among the elderly with lower BMI, providing valuable guidance for medical staff.

Non-linear association between air pollutants and secondary sensitive skin in acne patients

BACKGROUND

There is a growing number of patients suffering from sensitive skin secondary to acne, but its prevalence and influencing factors are not yet well-understood.

OBJECTIVE

The aim of this study is to investigate the nonlinear relationship between air pollutants and secondary sensitive skin in acne patients.

METHODS

A cross-sectional study comprising 4325 acne outpatients in China was carried out between September 2021 and December 2022, employing a simple random sampling approach. Air pollutants data was derived from the nearest air quality monitoring station corresponding to the subjects' residential locations. Furthermore, socio-economic characteristics, biological attributes, and lifestyle data of patients were acquired via questionnaire surveys. The data were subsequently analyzed utilizing the XGBoost machine learning model.

RESULTS

A nonlinear relationship has been observed between secondary sensitive skin in acne patients and various factors, including particulate matter (PM2.5), inhalable particulate matter (PM10), ozone (O3), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), the severity of depression, different levels of exercise intensity, acne grading, frequency of sunscreen application, gender, and age.

CONCLUSION

The occurrence of secondary sensitive skin in acne patients be mitigated through the implementation of measures such as the control of air pollutant emissions, regulation of negative emotions, and improvement of personal lifestyle.

Biomechanical and biochemical changes in murine skin during development and aging

Aging leads to biochemical and biomechanical changes in skin, with biological and functional consequences. Despite extensive literature on skin aging, there is a lack of studies which investigate the maturation of the tissue and connect the microscopic changes in the skin to its macroscopic biomechanical behavior as it evolves over time. The present work addresses this knowledge gap using multiscale characterization of skin in a murine model considering newborn, adult and aged mice. Monotonic uniaxial loading, tension relaxation with change of bath, and loading to failure tests were performed on murine skin samples from different age groups, complemented by inflation experiments and atomic force microscopy indentation measurements. In parallel, skin samples were characterized using histological and biochemical techniques to assess tissue morphology, collagen organization, as well as collagen content and cross-linking. We show that 1-week-old skin differs across nearly all measured parameters from adult skin, showing reduced strain stiffening and tensile strength, a thinner dermis, lower collagen content and altered crosslinking patterns. Surprisingly, adult and aged skin were similar across most biomechanical parameters in the physiologic loading range, while aged skin had lower tensile strength and lower stiffening behavior at large force values. This correlates with altered collagen content and cross-links. Based on a computational model, differences in mechanocoupled stimuli in the skin of the different age groups were calculated, pointing to a potential biological significance of the age-induced biomechanical changes in regulating the local biophysical environment of dermal cells. STATEMENT OF SIGNIFICANCE: Skin microstructure and the emerging mechanical properties change with age, leading to biological, functional and health-related consequences. Despite extensive literature on skin aging, only very limited quantitative data are available on microstructural changes and the corresponding macroscopic biomechanical behavior as they evolve over time. This work provides a wide-range multiscale mechanical characterization of skin of newborn, adult and aged mice, and quantifies microstructural correlations in tissue morphology, collagen content, organization and cross-linking. Remarkably, aged skin retained normal hydration and normal biomechanical function in the physiological loading range but showed significantly reduced properties at super-physiological loading. Our data show that age-related microstructural differences have a profound effect not only on tissue-level properties but also on the cell-level biophysical environment.

Applying Object Detection and Large Language Model to Establish a Smart Telemedicine Diagnosis System with Chatbot: A Case Study of Pressure Injuries Diagnosis System

Background: The scarcity of medical resources and personnel has worsened due to COVID-19. Telemedicine faces challenges in assessing wounds without physical examination. Evaluating pressure injuries is time consuming, energy intensive, and inconsistent. Most of today's telemedicine platforms utilize graphical user interfaces with complex operational procedures and limited channels for information dissemination. The study aims to establish a smart telemedicine diagnosis system based on YOLOv7 and large language model. Methods: The YOLOv7 model is trained using a clinical data set, with data augmentation techniques employed to enhance the data set to identify six types of pressure injury images. The established system features a front-end interface that includes responsive web design and a chatbot with ChatGPT, and it is integrated with a database for personal information management. Results: This research provides a practical pressure injury staging classification model with an average F1 score of 0.9238. The system remotely provides real-time accurate diagnoses and prescriptions, guiding patients to seek various medical help levels based on symptom severity. Conclusions: This study establishes a smart telemedicine auxiliary diagnosis system based on the YOLOv7 model, which possesses capabilities for classification and real-time detection. During teleconsultations, it provides immediate and accurate diagnostic information and prescription recommendations and seeks various medical assistance based on the severity of symptoms. Through the setup of a chatbot with ChatGPT, different users can quickly achieve their respective objectives.

Decreased proteasome function increases oxidative stress in the early stage of pressure ulcer development

The aging process in the elderly results in heightened skin fragility associated with various disorders, including pressure ulcers (PUs). Despite the high incidence of PUs in the elderly population, there is a limited body of research specifically examining the impact of aging on the development of pressure ulcers. Therefore, investigating age-related physiological abnormalities is essential to elucidate the pathogenesis of PUs. Ischemia-reperfusion (I/R) injury and the subsequent oxidative stress caused by reactive oxygen species (ROS) play essential roles in the early stage of PUs. In this study, we used a mouse model of proteasomal dysfunction with an age-related phenotype to examine the role of proteasome activity in cutaneous I/R injury in vivo. Decreased proteasome function did not affect the expression of inflammatory cytokines and adhesion molecules in the I/R area in transgenic mice; however, proteasome inhibition increased oxidative stress that was not attenuated by activation of the oxidative stress response mediated by NF-E2-related factor 2 (Nrf2). In dermal fibroblasts (FCs) subjected to hypoxia-reoxygenation (H/R), proteasome inhibition induced oxidative stress and ROS production, and Nrf2 activation did not adequately upregulate antioxidant enzyme expression, possibly leading to antioxidant/oxidant imbalance. The free radical scavenger edaravone had protective effects against I/R injury in vivo and decreased oxidative stress in FCs treated with a proteasome inhibitor and subjected to H/R in vitro. The results suggest that the age-related decline in proteasome activity promotes cutaneous I/R injury-induced oxidative stress, and free radical scavengers may exert protective effects by preventing oxidative stress in the early stage of PUs.

Positive and negative feedback regulation of the TGF-β1 explains two equilibrium states in skin aging

During aging, skin homeostasis is essential for maintaining appearance, as well as biological defense of the human body. In this study, we identified thrombospondin-1 (THBS1) and fibromodulin (FMOD) as positive and negative regulators, respectively, of the TGF-β1-SMAD4 axis in human skin aging, based on in vitro and in vivo omics analyses and mathematical modeling. Using transcriptomic and epigenetic analyses of senescent dermal fibroblasts, TGF-β1 was identified as the key upstream regulator. Bifurcation analysis revealed a binary high-/low-TGF-β1 switch, with THBS1 as the main controller. Computational simulation of the TGF-β1 signaling pathway indicated that THBS1 expression was sensitively regulated, whereas FMOD was regulated robustly. Results of sensitivity analysis and validation showed that inhibition of SMAD4 complex formation was a promising method to control THBS1 production and senescence. Therefore, this study demonstrated the potential of combining data-driven target discovery with mathematical approaches to determine the mechanisms underlying skin aging.

Comparison of the Predictive Validity of Norton and Braden Scales in Determining the Risk of Pressure Injury in Elderly Patients

AIM

To compare the reliability and predictive validity of Norton and Braden scales in determining the risk of pressure injury in elderly patients.

DESIGN

This research used a comparative design. One hundred thirty elderly patients participated in the study.

METHODS

The daily pressure injury risk of participants was evaluated by a researcher using both the Norton and Braden scales in a consecutive manner.

RESULTS

The mean age of patients was 75.1 ± 8.5 years, and that for those without and with pressure injury development was 75.0 ± 8.3 years and 76.1 ± 9.7 years (P < .001), respectively. The reliability coefficients of the Norton and Braden scales were .82 and .89, respectively. The sensitivity, specificity, and positive and negative predictive values of the Norton Scale were 100%, 40.7%, 20.2%, and 100%, and those of the Braden Scale were 100%, 32.7%, 18.3%, and 100%, respectively.

CONCLUSIONS

The reliability of both scales for elderly patients was found to be high, and their ability to differentiate patients at risk was comparable. However, both scales had low specificity. Further research is needed to develop scales that have higher predictive validity for the elderly population, taking into account other risk factors that influence total scale scores.

Dermatology Consultation in the Geriatrics Department of a Tertiary Hospital in China: A Retrospective Study of 178 Patients

Objective

Dermatological consultation plays an important role in diagnosing and treating skin diseases in the Department of Geriatrics. The objective of this study is to provide an analysis of the factors leading geriatric inpatients to seek dermatological consultation, aiming to facilitate accurate diagnosis and effective treatment of skin diseases by healthcare professionals specializing in geriatrics and dermatology.

Methods

The electronic health records of hospitalized patients in the Department of Geriatrics who applied for dermatological consultation at the Second Hospital of Shandong University from June 1, 2022, to June 1, 2023, were retrieved. Sex, age, number of consultations, reason for dermatology consultation, and final diagnosis by dermatologists were reviewed.

Results

A total of 216 consultations of 178 patients (n=178, 95 men and 83 women) were collected in this study, of whom 153 (86.0%) required only one consultation, 19 (10.7%) required two consultations, and 4 (2.2%) required three consultations. The reasons for dermatology consultations were divided into three categories: the first was for the definitive diagnosis of a new skin condition that developed during the patient's hospitalization (n=165, 76.4%), the second was for the follow-up of the condition and adjustment of medication (n=40, 18.5%), and the third was for the evaluation of the patient's disease that existed before admission to the hospital (n=11, 5.1%). In 165 consultations, most of these diseases (n=131, 79.4%) can be diagnosed by patients' conscious symptoms and clinical manifestations. Some of them need to be diagnosed or differentially diagnosed with the help of supplementary examinations, such as microscopic examination of scabies or fungi, and pathological examination.

Conclusion

This study summarized the reasons for dermatology consultations for geriatric inpatients and found that dermatitis/eczema and infectious diseases were the common types of diseases consulted. The findings of this study contribute to the enhanced comprehension and management of dermatological conditions in hospitalized patients by geriatricians, as well as facilitating more efficient diagnosis and treatment by dermatologists.

Pressure and Skin: A Review of Disease Entities Driven or Influenced by Mechanical Pressure

Skin perceives and reacts to external mechanical forces to create resistance against the external environment. Excessive or inappropriate stimuli of pressure may lead to cellular alterations of the skin and the development of both benign and malignant skin disorders. We conducted a comprehensive literature review to delve into the pressure-induced and aggravated skin disorders and their underlying pressure-related mechanisms. Dysregulated mechanical responses of the skin give rise to local inflammation, ischemia, necrosis, proliferation, hyperkeratosis, impaired regeneration, atrophy, or other injurious reactions, resulting in various disease entities. The use of personal devices, activities, occupations, weight bearing, and even unintentional object contact and postures are potential scenarios that account for the development of pressure-related skin disorders. The spectrum of these skin disorders may involve the epidermis (keratinocytes and melanocytes), hair follicles, eccrine glands, nail apparatuses, dermis (fibroblasts, mast cells, and vasculature), subcutis, and fascia. Clarifying the clinical context of each patient and recognizing how pressure at the cellular and tissue levels leads to skin lesions can enhance our comprehension of pressure-related skin disorders to attain better management.

Aging in the dermis: Fibroblast senescence and its significance

Skin aging is characterized by changes in its structural, cellular, and molecular components in both the epidermis and dermis. Dermal aging is distinguished by reduced dermal thickness, increased wrinkles, and a sagging appearance. Due to intrinsic or extrinsic factors, accumulation of excessive reactive oxygen species (ROS) triggers a series of aging events, including imbalanced extracellular matrix (ECM) homeostasis, accumulation of senescent fibroblasts, loss of cell identity, and chronic inflammation mediated by senescence-associated secretory phenotype (SASP). These events are regulated by signaling pathways, such as nuclear factor erythroid 2-related factor 2 (Nrf2), mechanistic target of rapamycin (mTOR), transforming growth factor beta (TGF-β), and insulin-like growth factor 1 (IGF-1). Senescent fibroblasts can induce and accelerate age-related dysfunction of other skin cells and may even cause systemic inflammation. In this review, we summarize the role of dermal fibroblasts in cutaneous aging and inflammation. Moreover, the underlying mechanisms by which dermal fibroblasts influence cutaneous aging and inflammation are also discussed.

A self-healing hydrogel wound dressing based on oxidized Bletilla striata polysaccharide and cationic gelatin for skin trauma treatment

Skin trauma presents significant treatment challenges in clinical settings. Hydrogels made from naturally-derived polysaccharide have demonstrated great potential in wound healing. Here, a novel in-situ crosslinked self-healing hydrogel was prepared using oxidized Bletilla striata polysaccharide (BSP) and cationic gelatin via a Schiff-base reaction without the need for any chemical crosslinkers. Similar to the natural extracellular matrix, the BSP-gelatin hydrogel (BG-gel) exhibited typical viscoelastic characteristics. The rheological properties, mechanical behavior, porous structure, and degradation performance of BG-gel could be adjusted by changing the aldehyde group content of BSP. Importantly, the hydrogel showed superior hemostatic performance in mouse tail amputation and rat liver incision models. It significantly facilitated wound healing by promoting hair follicles regeneration, blood vessels repair, collagen deposition, and inducing skin tissue remodeling via increased CD31 expression in a full-thickness skin wound rat model. This multifunctional hydrogel holds potential as a wound dressing for skin trauma, offering both hemostasis and expedited healing.

Balanced chemical reactivity, antimicrobial properties and biocompatibility of decellularized dermal matrices for wound healing

The prevention of bacterial infection and prompt wound repair are crucial considerations when local skin tissue is compromised by burns, cuts, or similar injuries. Porcine acellular dermal matrix (pADM) is a commonly employed biological material in wound repair due to its inherent natural properties. Nonetheless, the pADM's primary constituent, collagen fibers, lacks antimicrobial properties and is vulnerable to bacterial infection when used in the treatment of incompletely debrided wounds. Meanwhile, conventional antimicrobial agents primarily consist of chemical compounds that exhibit inadequate biocompatibility and biological hazards. This research endeavors to create an antimicrobial collagen scaffold dressing utilizing the Schiff base reaction through the incorporation of oxidized chitosan diquaternary (ODHTCC) salt into the pADM. Compared with the unmodified pADM, ODHTCC-pADM (OD-pA) still retained the three-stranded helical structure of natural collagen. At an ODHTCC cross-linker concentration of 4%, the thermal denaturation temperature of OD-pA was 85 °C. According to the enzymatic degradation resistance test in vitro, the degradation resistance of OD-pA to type I collagenase was significantly improved compared with that of the uncross-linked pADM. In addition, OD-pA exhibited good antibacterial properties, with inhibition rates of 95.6% and 99.9% for E. coli and Staphylococcus aureus, respectively, and a cytotoxicity level 1, meeting the in vitro requirements of national biomedical materials. In vivo experiments showed that the OD-pA scaffold could better promote wound healing and more effectively promote the positive expression of bFGF, PDGF and VEGF. In conclusion, OD-pA has struck a balance between antibacterial properties, chemical reaction properties and biocompatibility, ultimately achieving controllability, and has broad application prospects in the field of antibacterial biomedical materials.

A review of factors influencing sensitive skin: an emphasis on built environment characteristics

Background

Sensitive skin (SS) is a condition characterized by hyperreactivity. Impacting around 37 percent of the worldwide population and exerting an influence on the quality of life for affected individuals. Its prevalence rate has increased due to factors such as elevating stress levels and deteriorating environmental conditions. The exposome factors influencing SS have extended from demographic, biological attributes, and lifestyle to external environments. Built environments (BEs) have demonstrated as root drivers for changes in behaviors and environmental exposure which have the potential to trigger SS, but the review of the associations between BEs and SS is currently lacking.

Objective

This review aims to achieve two primary objectives: (1) Examine exposome factors that exert influence on SS at the individual and environmental levels. (2) Develop a theoretical framework that establishes a connection between BEs and SS, thereby offering valuable insights into the impact of the built environment on this condition.

Methods

An extensive literature search was carried out across multiple fields, including sociology, epidemiology, basic medicine, clinical medicine, and environmental research, with a focus on SS. To identify pertinent references, renowned databases such as PubMed, Web of Science, and CNKI were utilized.

Results

SS is the outcome of interactions between individual attributes and environmental factors. These influencing factors can be categorized into five distinct classes: (1) demographic and socioeconomic characteristics including age, gender, and race; (2) physiological and biological attributes such as emotional changes, skin types, sleep disorders, and menstrual cycles in women; (3) behavioral factors, such as spicy diet, cosmetic use, alcohol consumption, and physical exercise; (4) natural environmental features, including climate conditions and air pollution; (5) built environmental features such as population density, green space availability, road network density, and access to public transportation, also have the potential to affect the condition.

Conclusion

The importance of interdisciplinary integration lies in its ability to ascertain whether and how BEs are impacting SS. By elucidating the role of BEs in conjunction with other factors in the onset of SS, we can provide guidance for future research endeavors and the formulation of interventions aimed at mitigating the prevalence of SS.

Nipple-Sparing Mastectomies in Patients over the Age of 60 Years: Factors Associated with Surgical Outcomes

BACKGROUND

Nipple-sparing mastectomy (NSM) outcomes in the elderly have not been well characterized. The goal of this study was to evaluate NSM outcomes in patients over age 60.

PATIENTS AND METHODS

A single-institution retrospective cohort study was performed for NSM patients over the age of 60 from January 2004 to January 2022. Demographic, intraoperative, and postoperative variables were collected.

RESULTS

We identified 136 women who underwent a total of 200 NSMs at a mean age 65.2 years and with mean body mass index of 25. Most (56%) had invasive breast cancer, requiring neoadjuvant chemotherapy in 15%, and 17.5% had radiation prior to NSM. A total of 91% had immediate tissue expander placement. The infection rate was 19%, with 11.5% requiring expander explantation in the follow-up period. In binomial logistic regression analysis, prior radiation increased the odds of any complication by 2.9 (OR 2.93, CI 1.30-6.58, p = 0.009) and increased the odds of infection by 5.7 (OR 5.70, CI 1.95-16.66, p = 0.001), but no associations were seen for other covariates including age, comorbidities, prior chemotherapy, or presence of invasive disease. Diabetes increased the odds of wound breakdown specifically by 9.0 (OR 8.97, CI 2.01-39.92, p = 0.004). Local recurrence was 3% in mean 3.4-year follow-up.

CONCLUSIONS

Our data support NSM in patients over the age of 60 years with acceptable outcomes within the standard of care. Locoregional recurrence was within the cited range of 0-5%, and only diabetes and prior radiation were associated with reconstructive complications. NSM should thus be offered when appropriate regardless of increased age to achieve oncologic and reconstructive goals.

The Pressurized Skin: A Review on the Pathological Effect of Mechanical Pressure on the Skin from the Cellular Perspective

Since human skin is the primary interface responding to external mechanical stimuli, extrinsic forces can disrupt its balanced microenvironment and lead to cutaneous lesions. We performed this review to delve into the pathological effects of mechanical pressure on skin from the cellular perspective. Fibroblasts of different subsets act as heterogeneous responders to mechanical load and express diverse functionalities. Keratinocytes relay mechanical signals through mechanosensitive receptors and the ensuing neurochemical cascades to work collaboratively with other cells and molecules in response to pressure. Mast cells release cytokines and neuropeptides, promoting inflammation and facilitating interaction with sensory neurons, while melanocytes can be regulated by pressure through cellular and molecular crosstalk. Adipocytes and stem cells sense pressure to fine-tune their regulations of mechanical homeostasis and cell differentiation. Applying mechanical pressure to the skin can induce various changes in its microenvironment that potentially lead to pathological alterations, such as ischemia, chronic inflammation, proliferation, regeneration, degeneration, necrosis, and impaired differentiation. The heterogeneity of each cellular lineage and subset from different individuals with various underlying skin conditions must be taken into consideration when discussing the pathological effects of pressure on the skin. Thus, elucidating the mechanotransduction and mechanoresponsive pathways from the cellular viewpoint is crucial in diagnosing and managing relevant dermatological disorders.

Evaluation of Microvascular Autologous Breast Reconstruction in Patients Older Than 60 Years

BACKGROUND

While free-flap breast reconstruction becomes more common, it is still approached with caution in older patients. Outcomes in the elderly population have not been well characterized, especially with regard to donor-site sequalae. This study compares microvascular autologous breast reconstruction outcomes in patients older and younger 60 years.

METHODS

A single-institution retrospective review was performed for microvascular autologous breast reconstruction from January 2004 through January 2021. Demographic, intraoperative, and postoperative variables, including breast flap and donor-site complications, were evaluated.

RESULTS

Five hundred forty-five breast free flaps were identified, of which 478 (87.8%) were performed on patients younger than 60 years (mean, 46.2 years) and 67 (12.2%) older than 60 years (mean, 64.8 years; P = 0.000). Hyperlipidemia was significantly higher in older patients (19.4% vs 9.6%, P = 0.016). Mean operative time was 46.3 minutes faster in the older cohort ( P = 0.030). There were no significant differences in free-flap loss, venous congestion, takeback, hematoma, seroma, wound healing, or infection. Interestingly, there were significantly more total breast flap complications (28.5% vs 16.4%, P = 0.038) and higher rates of fat necrosis (9.6% vs 1.5%, P = 0.026) in the younger cohort. Significantly more abdominal donor-site complications (43.3% vs 21.3%, P = 0.000) were seen in the older people, with increased wound breakdown ( P = 0.000) and any return to the operating room (20.9% vs 9.8%, P = 0.007). Older patients were also significantly more likely to require surgical correction of an abdominal bulge or hernia (10.4% vs 4%, P = 0.020). The mean follow-up was 1.8 years.

CONCLUSIONS

Our data showed no worsening of individual breast flap outcomes in the older people. However, there were significantly more abdominal complications including surgical correction of abdominal bulge and hernia. This may be related to the inherent qualities of tissue aging and should be taken into consideration for flap selection. These results support autologous breast reconstruction in patients older than 60 years, but patients should be counseled regarding potentially increased abdominal donor-site sequelae.

Engineered NF-κB siRNA-encapsulating exosomes as a modality for therapy of skin lesions

Introduction

Despite the protection and management of skin has been paid more and more attention, effective countermeasures are still lacking for patients suffering from UV or chemotherapy with damaged skin. Recently, gene therapy by small interfering RNA (siRNA) has emerged as a new therapeutic strategy for skin lesions. However, siRNA therapy has not been applied to skin therapy due to lack of effective delivery vector.

Methods

Here, we develop a synthetic biology strategy that integrates the exosomes with artificial genetic circuits to reprogram the adipose mesenchymal stem cell to express and assemble siRNAs into exosomes and facilitate in vivo delivery siRNAs for therapy of mouse models of skin lesions.

Results

Particularly, siRNA enriched exosomes (si-ADMSC-EXOs) could be directly taken up by the skin cells to inhibit the expression of skin injury related genes. When mice with skin lesions were smeared with si-ADMSC-EXOs, the repair of lesioned skin became faster and the expression of inflammatory cytokines were decreased.

Discussion

Overall, this study establishes a feasible therapeutic strategy for skin injury, which may offer an alternative to conventional biological therapies requiring two or more independent compounds.

Epidermal thickness in healthy humans: A systematic review and meta-analysis

Several skin diseases are characterised by epidermal alterations affecting epidermal thickness. Reference values of epidermal thickness in healthy humans and knowledge of possible differences regarding age, sex, skin phototype, and ethnic origin are essential in research and in clinical practice. The objectives of this systematic review were to provide epidermal thickness reference values for healthy human skin and describe possible effects of measurement methods, age, sex, ethnic origin, and skin phototype. A combined search in the databases Medline and Embase, and other sources was conducted. Searches covered a period from 1946 to 3^rd June 2020. Included studies were primary observational and interventional studies providing means and spread values of epidermal thickness estimates in healthy humans, with clear reporting of skin area, age and measurement method, and optional reporting of sex, ethnic origin and skin phototype. Data were extracted per skin area and pooled in random-effects models. 142 studies were included in the qualitative synthesis and 133 in the meta-analysis. Pooled epidermal thickness estimates were calculated for 37 skin areas. The lowest epidermal thickness of 31.2 (95% CI 27.8 to 34.6) μm was reported for the penis, and the highest of 596.6 (95% CI 443.9 to 749.3) μm for the plantar aspect of the foot. Differences of epidermal thickness estimates obtained by histology, optical coherence tomography and laser scanning microscopy were minor. High-frequency ultrasonography produces systematically higher values. Epidermis was thinner in aged skin. Differences between sexes and among ethnic origins where minor. Epidermal thickness reference values are provided for 37 skin areas. In conclusion, the epidermis tends to become thinner by ageing and does not seem to be influenced by sex. Histology, optical coherence tomography and laser scanning microscopy might be used interchangeably to measure epidermal thickness, whereas high-frequency ultrasound should not be used.