Skin tissue cholesterol (SkinTc) is related to angiographically-defined cardiovascular disease

Therapeutic Effects of Statins: Promising Drug for Topical and Transdermal Administration

Statins are HMG-CoA reductase inhibitors and decrease plasma low-density lipoprotein cholesterol (LDL-C) levels. They are well tolerated, and because of their LDL-C-lowering effect, they are utilized to decrease the risk of atherosclerosis and cardiovascular disease. However, statins have pleiotropic effects, including immunomodulatory, anti-inflammatory, antioxidant, and anticancer. Currently, oral administration is the only Food and Drug Administration (FDA)-approved route of administration for statins. However, other administration routes have demonstrated promising results in different pre-clinical and clinical studies. For instance, statins also seem beneficial in dermatitis, psoriasis, vitiligo, hirsutism, uremic pruritus, and graft-versus-host disease. Topically applied statins have been studied to treat seborrhea, acne, rhinophyma, and rosacea. They also have beneficial effects in contact dermatitis and wound healing in animal studies, (HIV) infection, osseointegration, porokeratosis, and some ophthalmologic diseases. Topical and transdermal application of statins is a non-invasive drug administration method that has shown significant results in bypassing the first-pass metabolism in the liver, thereby reducing possible adverse effects. This study reviews the multifaceted molecular and cellular impacts of statins, their topical and transdermal application, novel delivery systems, such as nanosystems for topical and transdermal administration and the challenges concerning this approach.

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.

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.

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.

Usefulness of increased skin cholesterol to identify individuals at increased cardiovascular risk (from the Predictor of Advanced Subclinical Atherosclerosis study)

In patients with symptomatic coronary heart disease, skin cholesterol (SC) content is associated with the presence and extent of coronary artery disease; however, its relation to subclinical arterial disease in asymptomatic patients is unknown. The purpose of this study was to determine the relations between SC and carotid intima-media thickness (CIMT) in asymptomatic subjects across a wide range of cardiovascular risk. SC was measured using a noninvasive assay. CIMT and carotid plaque presence were determined by high-resolution B-mode ultrasound. Associations among SC, CIMT, carotid plaque presence, and cardiovascular risk factors were evaluated by multivariable logistic regression analyses. SC and CIMT were measured in 565 asymptomatic subjects (57 +/- 10 years of age, 38% women) from 6 sites in North America. The mean Framingham 10-year cardiovascular risk was 8.4 +/- 7.2%. A 10-U increase in SC was associated with a 12% increase in the odds of having increased CIMT (p = 0.006) and a 15% increase in carotid plaque presence (p = 0.002). Odds ratios (95% confidence intervals) associated with SC >110 U were 2.19 (1.25 to 3.85, p = 0.006) for increased CIMT and 2.89 (1.61 to 5.19, p <0.001) for carotid plaque presence. In conclusion, SC identified the presence of advanced subclinical atherosclerosis. The relations among increasing SC, increasing CIMT, and carotid plaque presence were consistent across all levels of cardiovascular risk and were independent of cardiovascular risk factors. SC may be a useful test for cardiovascular risk prediction.

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.

Elevated skin tissue cholesterol levels and myocardial infarction

BACKGROUND

Skin cholesterol has been associated with coronary artery disease, extent of angiographic disease and inflammatory markers such as hs-CRP. Based on these findings we sought to determine whether skin cholesterol was associated with myocardial infarction (MI).

METHODS

Patients (N = 649) underwent diagnostic catheterization and concurrent skin cholesterol measurement. History of MI was determined at the time of hospitalization.

RESULTS

Patients with a history of MI (n = 225, 35%) had significantly higher skin cholesterol than those without MI (127+/-29 versus 120+/-20, p = 0.002). The odds ratio for high skin cholesterol (for MI) was 1.6 (95% CI = 1.1, 2.6; p = 0.01) after adjustment for traditional risk and extent of angiographic disease.

CONCLUSION

Skin cholesterol may indicate increased risk of coronary-related events rather than simply the presence of angiographic narrowing.

Skin cholesterol content identifies increased carotid intima-media thickness in asymptomatic adults

BACKGROUND

A noninvasive assay to measure skin Tc recently has become available for use in the outpatient setting as a cardiovascular (CV) risk prediction tool. The purpose of this study was to determine whether skin tissue cholesterol content (skin Tc) levels are associated with increased carotid intima-media thickness (CIMT) after adjusting for known CV risk factors and Framingham CV risk.

METHODS

Consecutive patients without known vascular disease who were referred for determination of CIMT underwent B-mode ultrasonography of the carotid arteries and measurement of skin Tc using a noninvasive assay. Use of medications, cardiac risk factors, and Framingham 10-year CV risk were determined prospectively. Multivariable regression was used to determine predictors of increased CIMT.

RESULTS

Among 81 subjects, the mean (SD) age was 55.6 (7.7) years and the mean skin Tc was 95.9 (18.3) U. Carotid intima-media thickness was significantly higher among individuals in the highest quartile of skin Tc (0.87 vs 0.76 mm, P = .011). In multivariable analyses, skin Tc was associated with increased CIMT even after adjusting for age, sex, glucose, systolic blood pressure, total/high-density lipoprotein cholesterol ratio, and use of lipid-lowering therapy (odds ratio [OR] per 10-unit increase = 1.590, 95% CI 1.525-1.658, P = .031). Skin Tc also was associated with increased CIMT after adjustment for Framingham risk (OR = 1.341, 95% CI 1.302-1.380, P = .048).

CONCLUSIONS

Skin Tc is an easy-to-measure, noninvasive marker that can help identify subclinical atherosclerosis in asymptomatic middle-aged adults, even after controlling for risk factors and CV risk predicted by the Framingham model.

Skin tissue cholesterol assay correlates with presence of coronary calcium

BACKGROUND

Keratinocytes maintain cholesterol homoeostasis using LDL and HDL-scavenger receptor pathways implicated in atherosclerosis. We tested whether skin tissue cholesterol (SkTC) is associated with subclinical atherosclerosis, assessed using carotid intima-medial thickness (IMT) and coronary artery calcification (CAC).

METHODS

Two hundred and twenty two subjects were recruited from the Baltimore site of the Multi-Ethnic Study of Atherosclerosis (MESA). Baseline MESA examination included fasting blood collection, IMT measurement by B-mode ultrasound and CAC determination by helical CT. SkTC was measured using the Cholesterol 1, 2, 3 kit (IMI Inc., Canada).

RESULTS

SkTC was significantly higher if CAC was present in Caucasians (p = 0.04) but not African-Americans. SkTC was not significantly correlated with IMT in either group. Using multiple logistic regression adjusting for age, sex and serum lipids, a 1-standard deviation higher SkTC was associated with 187% higher odds of the presence of CAC in Caucasians (p < 0.01) but no significant difference in odds for African-Americans. In subjects in whom CAC was present, the extent of CAC was not related to the SkTC in multiple linear regressions.

CONCLUSIONS

SkTC was associated with the presence of CAC independently of serum lipids/lipoproteins in Caucasians but not African-Americans. SkTC may provide a useful indicator of subclinical atherosclerosis in Caucasians.