Elevated skin tissue cholesterol levels and myocardial infarction

Structural and Functional Analysis of Excised Skins and Human Reconstructed Epidermis with Confocal Raman Spectroscopy and in Microfluidic Diffusion Chambers

Several ex vivo and in vitro skin models are available in the toolbox of dermatological and cosmetic research. Some of them are widely used in drug penetration testing. The excised skins show higher variability, while the in vitro skins provide more reproducible data. The aim of the current study was to compare the chemical composition of different skin models (excised rat skin, excised human skin and human-reconstructed epidermis) by measurement of ceramides, cholesterol, lactate, urea, protein and water at different depths of the tissues. The second goal was to compile a testing system, which includes a skin-on-a-chip diffusion setup and a confocal Raman spectroscopy for testing drug diffusion across the skin barrier and accumulation in the tissue models. A hydrophilic drug caffeine and the P-glycoprotein substrate quinidine were used in the study as topical cream formulations. The results indicate that although the transdermal diffusion of quinidine is lower, the skin accumulation was comparable for the two drugs. The various skin models showed different chemical compositions. The human skin was abundant in ceramides and cholesterol, while the reconstructed skin contained less water and more urea and protein. Based on these results, it can be concluded that skin-on-a-chip and confocal Raman microspectroscopy are suitable for testing drug penetration and distribution at different skin layers within an exposition window. Furthermore, obese human skin should be treated with caution for skin absorption testing due to its unbalanced composition.

Non-invasive skin cholesterol testing: a potential proxy for LDL-C and apoB serum measurements

Background

Lipid management is the first line of treatment for decreasing the incidence of cardiovascular events in patients with coronary heart disease (CHD), and a variety of indicators are used to evaluate lipid management. This work analyses the differences in LDL-C and apoB for lipid management evaluation, as well as explores the feasibility of skin cholesterol as a marker that can be measured non-invasively for lipid management.

Methods

The prospective study enrolled 121 patients who had been diagnosed with acute coronary syndrome (ACS) at the department of emergency medicine of the First Affiliated Hospital of the USTC from May 2020 to January 2021, and the patients were grouped into Group I (n=53) and Group II (n=68) according to whether they had comorbid hyperlipidemia and/or diabetes mellitus. All patients were administered 10 mg/day of rosuvastatin and observed for 12 weeks. Lipid management was assessed on the basis of LDL-C and apoB, and linear correlation models were employed to assess the relationship between changes in these well accepted markers to that of changes in skin cholesterol.

Results

Out of 121 patients with ACS, 53 patients (43.80 %) had combined hyperlipidemia and/or diabetes mellitus (Group I), while 68 patients (56.20 %) did not (Group II). Cardiovascular events occur at earlier ages in patients with CHD who are comorbid for hyperlipidemia and/or diabetes (P<0.05). LDL-C attainment rate is lower than apoB attainment rate with rosuvastatin therapy (P<0.05), which is mainly attributable to patients with low initial LDL-C. Skin cholesterol reduction correlated with LDL-C reduction. (r=0.501, P<0.001) and apoB reduction (r=0.538, P<0.001). Skin cholesterol reduction continued over all time points measured.

Conclusions

Examination of changes in apoB levels give patients with low initial LDL-C more informative data on lipid management than LDL-C readings. In addition, non-invasive skin cholesterol measurements may have the potential to be used independently for lipid management evaluation.

The relationship between the severity of coronary artery disease and skin measurement parameters

PURPOSE

This study aimed to investigate the relationship between skin parameters and CAD.

MATERIALS AND METHODS

The study included 50 patients diagnosed with coronary artery disease as the patient group and 45 volunteers without any known coronary artery disease as the control group. The participants' skin TEWL, pH, temperature, electrical capacitance, sebum, and elasticity values were measured using noninvasive methods at the forehead, back, and forearm.

FINDINGS

Skin temperature was significantly higher in the back and forehead regions in the patient group. No difference was found between the sebum values of the patient and control groups at the back and forehead. A significantly higher result was obtained for the forearm area. The pH was significantly lower in the patients' forearm, although the obtained values were within the normal range. The TEWL was significantly higher in patients in all three regions. In terms of flexibility, R2 was significantly higher in the back and forehead regions of the patient group, and the R6 was significantly higher in the patient group in all three regions. In addition, there was no correlation between skin parameter and SYNTAX score increase measurements.

CONCLUSION

It can be suggested that skin sebum and TEWL measurements can be accepted as cheap and noninvasive methods of predicting CAD.

Confocal Raman spectroscopy: In vivo measurement of physiological skin parameters - A pilot study

BACKGROUND

In vivo application of confocal Raman spectroscopy (CRS) allows non-invasive depth measurement of the skin. Thereby obtained knowledge of the skin composition is essential to reliably assess the actual skin state. Besides other components, the skin cholesterol concentration is of interest; however, little is known about its connection to the cholesterol concentration quantified in venous blood.

OBJECTIVE

In this study, the skin composition of the volar forearm was characterised in vivo using CRS. In particular, the potential of CRS as a non-invasive method to determine cholesterol levels was validated.

METHODS

Raman spectra of the volar forearm of 15 participants were recorded twice within two weeks. Depth concentration profiles for major skin components were generated. Stratum corneum (SC) thickness was calculated from water concentration profiles. In order to examine the usability of dermal CRS for cholesterol level determination, results were compared to fasting total cholesterol values in venous blood as determined by an enzymatic method.

RESULTS

Depth concentration profiles for the skin components of interest showed a comparable curve progression for the participants. It was possible to link changes in concentration to physiological processes. Moreover, age-related differences could be found. Several novel mathematical approaches for the comparison of the skin cholesterol content and the blood cholesterol concentration have been developed. However, no correlation passed the Bonferroni multiple testing correction.

CONCLUSION

CRS serves as useful tool for the in vivo monitoring of skin components and hydration. Concentration depth profiles provide information about the current skin condition. No distinct correlation between the skin and blood cholesterol concentration was found within the scope of the present study. Concerning this matter, the heterogeneous distribution of cholesterol in the skin may be a factor influencing these results.

The relationship between skin cholesterol testing and parameters of cardiovascular risk: a systematic review

BACKGROUND

A potential correlation between skin cholesterol levels obtained via skin biopsy and evidence of underlying atherosclerosis has been reported. With the availability of a noninvasive method of skin cholesterol measurement, multiple studies investigated the association of skin cholesterol and traditional cardiovascular risk factors. We provide a systematic review of clinical data to assist physicians counselling patients that have undergone skin cholesterol testing and to provide a framework for future research.

METHODS

Multiple electronic databases were systematically searched for studies published from 1970 through February 2013. Selection criteria included English language, peer-reviewed studies that quantitatively examined the relationship between noninvasively measured skin cholesterol levels and indices of vascular disease or cardiovascular risk factors in human subjects.

RESULTS

We identified 9 cohorts reported in 11 studies. The studies suggest that skin cholesterol does not correlate with traditional markers of cardiovascular disease such as serum lipid values and inflammatory markers, and integrated risk scores (Framingham and Prospective Cardiovascular Münster [PROCAM]). Single studies reported a significant relationship between skin cholesterol levels and evidence of underlying atherosclerosis as implied by positive exercise testing, invasive coronary angiography, increased calcium scores in Caucasian patients, and presence of carotid plaque detected using B-mode ultrasound. Two studies identified a significant relationship using B-mode measurements of carotid intima medial thickening.

CONCLUSIONS

Skin cholesterol might be a marker of underlying vascular atherosclerosis. Further prospective investigations are warranted to establish utility of this point-of-care test for identifying subjects warranting formal cardiovascular risk assessment.

The outer frontier: the importance of lipid metabolism in the skin

The skin serves the vital function of providing a barrier between the hostile external environment and the host. While the skin has many important barrier functions, the two that are absolutely essential for survival are the barrier to the movement of water and electrolytes (permeability barrier) and the barrier against invasive and toxic microorganisms (antimicrobial barrier). Lipids play an essential role in the formation and maintenance of both the permeability and antimicrobial barriers. A hydrophobic extracellular lipid matrix in the stratum corneum composed primarily of ceramides, cholesterol, and free fatty acids provides the barrier to the movement of water and electrolytes. A variety of lipids, such as fatty alcohols, monoglycerides, sphingolipids, phospholipids, and in particular free fatty acids, have antimicrobial activity and contribute to the antimicrobial barrier. In addition to these essential functions, we will also review the ability of skin surface cholesterol to reflect alterations in systemic lipid metabolism and the risk of atherosclerosis.

Skin tissue cholesterol is not related to vascular occlusive disease

The objective of the present study was to evaluate the role of skin tissue cholesterol (SkinTc) in predicting the presence of atherosclerosis. SkinTc concentrations were determined in 318 consecutive patients by using the non-invasive PREVU POC Skin Sterol Test. Additionally, a complete lipid status and cardiovascular risk profile according to the PROCAM and Framingham scores as well as an evaluation by carotid duplex sonography and ankle-brachial blood pressure index testing was obtained from all patients. SkinTc concentrations did not differ significantly among patients suffering from cerebrovascular disease (CVD) and peripheral arterial disease (PAD) compared to the corresponding control groups and among patients with a calculated cardiovascular risk > 10% in 10 years compared to patients with a risk < 10% (all p > 0.05). Additionally, SkinTc concentrations were not significantly higher in the 245 patients with at least one documented atherosclerotic disease compared with the remaining 73 patients without evidence of atherosclerosis. In conclusion, SkinTc concentrations determined by the PREVU POC Skin SterolTest are not related to the presence of CVD and PAD or to an elevated cardiovascular risk, indicating that this parameter cannot be used as a reliable indicator of atherosclerosis.

Skin cholesterol adds to Framingham risk assessment

INTRODUCTION

It has been demonstrated that skin tissue cholesterol (SkinTc) is associated with angiographic disease. Now, we further delineate the relative risk of multivessel disease (>50% stenosis in at least two vessels) in the conjoint presence of high SkinTc and high traditional risk burden.

METHODS

Patients scheduled for angiography (N = 649) had SkinTc measured immediately prior to the procedure. Patients were classified according to the presence of high (>110) SkinTc and high (>10) Framingham global risk scores. Multivariable logistic regression models were used to estimate relative risk of multivessel disease for patients with isolated high skin tissue cholesterol, isolated high Framingham risk or conjoint high skin tissue cholesterol and high Framingham risk (each compared to neither factor elevated).

RESULTS

The mean age was 63 +/- 12 years and 33% (n = 214) were women. Thirty seven percent (n = 237) had angiographically determined multivessel disease. Patients with isolated high SkinTc showed a relative risk of multivessel disease of 1.6 (95% CI = 1.0-2.4), while patients with isolated high Framingham risk had an odds ratio of 1.8 (CI = 1.0-3.4). However, when both scores were elevated, risk of multivessel disease was increased 4.3 times (CI = 2.6-7.2) compared to neither elevated.

CONCLUSIONS

We see an independent, additive risk of concurrent multivessel disease when Framingham risk and skin cholesterol are both elevated. Skin tissue cholesterol may have value in further stratifying subjects with Framingham scores >10.