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Rakesh Gupta - One of the best experts on this subject based on the ideXlab platform.
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Molecular Dynamics Simulation Study of Skin Lipids: Effects of the Molar Ratio of Individual Components over a Wide Temperature Range B
The Journal of Physical Chemistry, 2020Co-Authors: Rakesh GuptaAbstract:Atomistic molecular dynamics (MD) simulations were employed to systematically investigate the effects of the molar ratio of the individual components cholesterol (CHOL), free fatty acid (FFA), and ceramides (CER) on the properties of the Skin Lipid bilayer over a wide temperature range (300–400 K). Several independent simulations were performed for bilayers comprised of only CER, CHOL, or FFA molecules as well as those made up of a mixture of CER:CHOL:FFA molecules in different molar ratios. It was found that CHOL increases the stability of the bilayer, since the mixed (CER:CHOL:FFA) 1:1:0, 1:1:1, and 2:2:1 bilayers remained stable until 400 K while the pure ceramide bilayer disintegrated around ∼390 K. It was also observed that CHOL reduces the volume spanned by ceramide molecules, thereby leading to a higher area per CER and FFA molecule in the mixed bilayer system. The CHOL molecule provided more rigidity to the mixed bilayer and led to a more ordered phase at elevated temperatures. The CHOL molecule provided fluidity to the bilayer below the phase transition temperature of CER and kept the bilayer rigid above the phase transition temperature. The FFA interdigitizes with CER molecules and increases the thickness of the bilayer, while rigid CHOL decreases the bilayer thickness. The presence of CHOL increases the compressibility of the bilayer which is responsible for the high barrier function of Skin. The CER molecule forms inter- and intramolecular hydrogen bonds, while CHOL only forms intermolecular hydrogen bonds.
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Computer-Aided Design of Nanoparticles for Transdermal Drug Delivery
Drug Delivery Systems, 2020Co-Authors: Rakesh Gupta, Beena RaiAbstract:Human Skin provides an excellent opportunity for drug delivery application. However, the delivery of hydrophilic drug and big protein molecules is challenging due to barrier provided by the top layer of Skin known as stratum corneum (SC). The chemical permeation enhancers or specialized carriers such as nanoparticles (NPs) are needed which can deliver drug molecules into the deeper layer. Here, we describe the in silico design of nanoparticle carriers using molecular dynamics (MD) simulations for the transdermal drug delivery application. At first, setup of a Skin Lipid bilayer model is demonstrated. Further, nanoparticles are designed based on the Monte Carlo simulation technique. These nanoparticles are then tested on Skin model using various MD simulation techniques.
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Effect of Chemical Permeation Enhancers on Skin Permeability: In silico screening using Molecular Dynamics simulations
Scientific Reports, 2019Co-Authors: Rakesh Gupta, Balarama Sridhar Dwadasi, Beena Rai, Samir MitragotriAbstract:Breaching of the Skin barrier is essential for delivering active pharmaceutical ingredients (APIs) for pharmaceutical, dermatological and aesthetic applications. Chemical permeation enhancers (CPEs) are molecules that interact with the constituents of Skin’s outermost and rate limiting layer stratum corneum (SC), and increase its permeability. Designing and testing of new CPEs is a resource intensive task, thus limiting the rate of discovery of new CPEs. In-silico screening of CPEs in a rigorous Skin model could speed up the design of CPEs. In this study, we performed coarse grained (CG) molecule dynamics (MD) simulations of a multilayer Skin Lipid matrix in the presence of CPEs. The CPEs are chosen from different chemical functionalities including fatty acids, esters, and alcohols. A multi-layer in-silico Skin model was developed. The CG parameters of permeation enhancers were also developed. Interactions of CPEs with SC Lipids was studied in silico at three different CPE concentrations namely, 1% w/v, 3% w/v and 5% w/v. The partitioning and diffusion coefficients of CPEs in the SC Lipids were found to be highly size- and structure-dependent and these dependencies are explained in terms of structural properties such as radial distribution function, area per Lipid and order parameter. Finally, experimentally reported effects of CPEs on Skin from the literature are compared with the simulation results. The trends obtained using simulations are in good agreement with the experimental measurements. The studies presented here validate the utility of in-silico models for designing, screening and testing of novel and effective CPEs.
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electroporation of Skin stratum corneum Lipid bilayer and molecular mechanism of drug transport a molecular dynamics study
Langmuir, 2018Co-Authors: Rakesh GuptaAbstract:The electroporation technique has been used significantly to increase drug permeation through the Skin. This technique relies on the application of short-timed (microseconds to millisecond) electric fields (generally, order of 50−-300 V) on the Skin to create microscopic pores. However, the molecular mechanism of pore formation, resulting in an enhanced flux of active molecules through the Skin, remains poorly understood. In this study, extensive atomistic molecular dynamics simulation of Skin Lipids [made up of ceramide (CER), cholesterol (CHOL), and free fatty acid (FFA)] has been performed at various external electric fields. We show for the first time the pore formation in the Skin Lipid bilayer during electroporation. We show the effect of the applied external electrical field (0.6–1.0 V/nm) on the pore formation dynamics in the Lipid bilayer of different sizes (154, 616, and 2464 Lipids) and compositions (CER/CHOL/FFA, 1:0:0, 1:0:1, 1:1:0, 1:1:1). The pore formation and resealing kinetics were diffe...
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In-silico design of nanoparticles for transdermal drug delivery application.
Nanoscale, 2018Co-Authors: Rakesh GuptaAbstract:Nanoparticles are used in the medical field for various applications like cell imaging, drug delivery, gene and si-RNA delivery, to name a few. Designing nanoparticles for a given application, purely based on the trial and error experimentation, requires a lot of time and effort. In this study we show that computer simulations could help in designing nanoparticles for drug delivery thus reducing the time and cost associated with their design, development and deployment. The permeation of nanoparticles, having various surface chemistries and patterns, through the Skin Lipid bilayer was studied using constrained and unconstrained molecular dynamics simulations. Interestingly, the permeation mechanism of nanoparticles having the same surface chemistry but different patterns was found to be completely different. Nanoparticles (NPs) were screened based on the free energy of permeation through the Skin Lipid bilayer. The behavior of the screened NPs was further validated with unconstrained simulations using the Skin Lipid bilayer. Nanoparticles thus screened through both of the techniques were further used for the co-delivery of a model protein into the Skin Lipid bilayer. It was observed that the nanoparticles having a 2 : 1 homogeneous ratio of hydrophobic to hydrophilic regions were the most promising in transdermal delivery of proteins. The obtained results are in line with the results of recent permeation experiments on cell and plasma membrane. Our study could help in in-silico design of nanoparticles for delivery of actives through Skin. These in-silico experiments thus could help speed up the development process by guiding formulation chemists.
Joke A. Bouwstra - One of the best experts on this subject based on the ideXlab platform.
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free fatty acids chain length distribution affects the permeability of Skin Lipid model membranes
Biochimica et Biophysica Acta, 2016Co-Authors: Masayuki Uchiyama, Gert S. Gooris, Masashi Oguri, E H Mojumdar, Joke A. BouwstraAbstract:Abstract The Lipid matrix in the stratum corneum (SC) plays an important role in the barrier function of the Skin. The main Lipid classes in this Lipid matrix are ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs). The aim of this study was to determine whether a variation in CER subclass composition and chain length distribution of FFAs affect the permeability of this matrix. To examine this, we make use of Lipid model membranes, referred to as stratum corneum substitute (SCS). We prepared SCS containing i) single CER subclass with either a single FFA or a mixture of FFAs and CHOL, or ii) a mixture of various CER subclasses with either a single FFA or a mixture of FFAs and CHOL. In vitro permeation studies were performed using ethyl-p-aminobenzoic acid (E-PABA) as a model drug. The flux of E-PABA across the SCS containing the mixture of FFAs was higher than that across the SCS containing a single FA with a chain length of 24 C atoms (FA C24), while the E-PABA flux was not effected by the CER composition. To select the underlying factors for the changes in permeability, the SCSs were examined by Fourier transform infrared spectroscopy (FTIR) and Small angle X-ray scattering (SAXS). All Lipid models demonstrated a similar phase behavior. However, when focusing on the conformational ordering of the individual FFA chains, the shorter chain FFA (with a chain length of 16, 18 or 20 C atoms forming only 11 m/m% of the total FFA level) had a higher conformational disordering, while the conformational ordering of the chains of the CER and FA C24 and FA C22 hardly did not change irrespective of the composition of the SCS. In conclusion, the conformational mobility of the short chain FFAs present only at low levels in the model SC Lipid membranes has a great impact on the permeability of E-PABA.
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the role of ceramide chain length distribution on the barrier properties of the Skin Lipid membranes
Biochimica et Biophysica Acta, 2014Co-Authors: E H Mojumdar, Gert S. Gooris, Z Kariman, L Van Kerckhove, Joke A. BouwstraAbstract:Abstract The Skin barrier function is provided by the stratum corneum (SC). The Lipids in the SC are composed of three Lipid classes: ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs) which form two crystalline lamellar structures. In the present study, we investigate the effect of CER chain length distribution on the barrier properties of model Lipid membranes mimicking the Lipid composition and organization of SC. The membranes were prepared with either isolated pig CERs (PCERs) or synthetic CERs. While PCERs have a wide chain length distribution, the synthetic CERs are quite uniform in chain length. The barrier properties were examined by means of permeation studies using hydrocortisone as a model drug. Our studies revealed a reduced barrier in Lipid membranes prepared with PCERs compared to synthetic CERs. Additional studies revealed that a wider chain length distribution of PCERs results in an enhanced hexagonal packing and increased conformational disordering of the Lipid tails compared to synthetic CERs, while the lamellar phases did not change. This demonstrates that the chain length distribution affects the Lipid barrier by reducing the Lipid ordering and density within the Lipid lamellae. In subsequent studies, the effect of increased levels of FFAs or CERs with a long acyl chain in the PCERs membranes was also studied. These changes in Lipid composition enhanced the level of orthorhombic packing, reduced the conformational disordering and increased the barrier of the Lipid membranes. In conclusion, the CER chain length distribution is an important key factor for maintaining a proper barrier.
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ceramides in the Skin Lipid membranes length matters
Langmuir, 2013Co-Authors: Barbora Školová, Joke A. Bouwstra, Gert S. Gooris, Barbora Janůsova, Jarmila Zbytovska, P Slepicka, Pavel Berka, Karel Palat, Alexandr Hrabalek, Kateřina VavrovaAbstract:Ceramides are essential constituents of the Skin barrier that allow humans to live on dry land. Reduced levels of ceramides have been associated with Skin diseases, e.g., atopic dermatitis. However, the structural requirements and mechanisms of action of ceramides are not fully understood. Here, we report the effects of ceramide acyl chain length on the permeabilities and biophysics of Lipid membranes composed of ceramides (or free sphingosine), fatty acids, cholesterol, and cholesterol sulfate. Short-chain ceramides increased the permeability of the Lipid membranes compared to a long-chain ceramide with maxima at 4–6 carbons in the acyl. By a combination of differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, Langmuir monolayers, and atomic force microscopy, we found that the reason for this effect in short ceramides was a lower proportion of tight orthorhombic packing and phase separation of continuous short ceramide-enriched domains with shorter lamellar period...
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Skin Lipid organization, composition and barrier function
International Journal of Cosmetic Science, 2008Co-Authors: Joke A. Bouwstra, Gert S. Gooris, Maria PonecAbstract:Citation: IFSCC Magazine, 10 (2007) (4) 297–307 The primary function of the Skin is to act as a barrier against unwanted influences from the environment and to protect the body from water loss. The barrier function of the Skin is located in the superficial layer of the Skin, the stratum corneum. The stratum corneum consists of dead cells filled with keratin and water, the corneocytes, embedded in Lipid regions. As the Lipid regions are the only continuous structure in the stratum corneum, they are considered to be very important for the Skin barrier function. The main Lipid classes are ceramides, cholesterol and free fatty acids. In this paper the Lipid organization in human stratum corneum is reviewed. In addition, the role the various Lipid classes play in Lipid organization is discussed using mixtures prepared from either native human ceramides or synthetic ceramides. Finally, a model is described which allows study of the relation between Lipid composition, organization and barrier function. This model is referred to as the stratum corneum substitute. Keywords: ceramides, FTIR, Lipid organization, stratum corneum, X-ray diffraction
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barrier characteristics of different human Skin types investigated with x ray diffraction Lipid analysis and electron microscopy imaging
Journal of Investigative Dermatology, 2000Co-Authors: Volker Schreiner, Gert S. Gooris, Stephan Pfeiffer, Ghita Lanzendorfer, Horst Wenck, Walter Diembeck, E Proksch, Joke A. BouwstraAbstract:The stratum corneum requires ceramides, cholesterol, and fatty acids to provide the cutaneous permeability barrier. The Lipids are organized in intercellular membranes exhibiting short- and long-periodicity lamellar phases. In recent years, the phase behavior of barrier Lipid mixtures has been studied in vitro . The relationship of human stratum corneum Lipid composition to membrane organization in vivo , however, has not been clearly established. Furthermore, the special function of the different ceramide species in the stratum corneum is largely unknown. We examined Lipid organization and composition of stratum corneum sheets from different subtypes of healthy human Skin (normal, dry, and aged Skin). Lipid organization was investigated using X-ray diffraction and demonstrated that the 4.4 nm peak attributed to the long periodicity phase was frequently missing for Skin with a low Cer(EOS)/Cer total ratio, indicating an important part for Cer(EOS), which contains ω-hydroxy fatty acid (O) ester-linked to linoleic acid (E) and amide-linked to sphingosine (S). A deficiency in the 4.4 nm peak was predominantly observed in young dry Skin. In one case of aged Skin, however, and less often in young normal Skin this peak was also missing. Furthermore, the ceramide composition of samples without the 4.4 nm peak showed a deficiency of Cer(EOH), which contains 6-hydroxy-4-sphingenine (H), and an increase in Cer(NS) and Cer(AS), which contain nonhydroxy (N) or α-hydroxy fatty acids (A). In addition, a 3.4 nm peak attributed to crystalline cholesterol occurred in most cases of aged and dry Skin, but was not observed in young normal Skin. Our results do not indicate a definite pattern of correlation between Lipid organization and types of human Skin. They demonstrate, however, that Cer(EOS) and Cer(EOH) are key elements for the molecular organization of the long periodicity lamellar phase in the human stratum corneum.
Kateřina Vavrova - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of 6-hydroxyceramide using ruthenium-catalyzed hydrosilylation–protodesilylation. Unexpected formation of a long periodicity lamellar phase in Skin Lipid membranes
RSC Advances, 2020Co-Authors: Andrej Kovacik, Lukas Opalka, Michaela Šilarová, Kateřina VavrovaAbstract:The synthesis of a ceramide with a 6-hydroxysphingosine base, a unique component of the human epidermal barrier, is reported. The key step involves a mild and selective trans-reduction of a triple bond using [Cp*Ru(CH3CN)3]PF6-catalyzed hydrosilylation followed by protodesilylation. The oxidation of sphingosine-based ceramide to 6-hydroxyceramide is also described. X-Ray powder diffraction on the model Skin Lipid membranes showed that 6-hydroxyceramide promotes the formation of a lamellar phase with 10.6 nm periodicity, which might explain why keratinocytes hydroxylate some ceramides at carbon 6.
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Permeability and microstructure of cholesterol-depleted Skin Lipid membranes and human stratum corneum
Journal of Colloid and Interface Science, 2018Co-Authors: Michaela Sochorova, Lukas Opalka, Andrej Kovacik, Petra Pullmannová, Pavla Audrlická, Martina Červená, Monika Kopečná, Kateřina VavrovaAbstract:Abstract Cholesterol (Chol) is one of the major Skin barrier Lipids. The physiological level of Chol in the stratum corneum (SC) appears to exceed its miscibility with other barrier Lipids, as some Chol is phase separated. Chol synthesis is essential for epidermal homeostasis, yet the role of these Chol domains in SC permeability is unknown. We investigated the impact of Chol depletion on the permeability properties and microstructure of model membranes and human SC. X-ray powder diffraction of membranes constructed from isolated human Skin ceramides or synthetic ceramides confirmed that only approximately half of the normal Chol amount can be incorporated in either long or short periodicity lamellar phases. The long periodicity Lipid arrangement persisted even in the absence of Chol. Infrared spectroscopy suggested that Chol had negligible effects on the Lipid chain order and packing at physiological Skin temperature. Chol depletion of the model membranes or isolated human SC did not compromise the barrier function to water and two model permeants. On the contrary, the membrane with the Chol content reduced to 40% of the normal value, where no separated Chol was observed, was significantly less permeable than the control. Thus, a 0.4:1:1 M ratio of Chol/ceramides/fatty acids appears sufficient for Skin Lipids to limit water loss and prevent the entry of environmental substances. We speculate that the SC Chol domains may have roles in the Skin other than barrier function.
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Effects of Ceramide and Dihydroceramide Stereochemistry at C-3 on the Phase Behavior and Permeability of Skin Lipid Membranes.
Langmuir, 2017Co-Authors: Andrej Kovacik, Petra Pullmannová, Jaroslav Maixner, Kateřina VavrovaAbstract:Ceramides (Cer) are key components of the Skin permeability barrier. Sphingosine-based CerNS and dihydrosphingosine-based CerNdS (dihydroCer) have two chiral centers; however, the importance of the correct stereochemistry in the Skin barrier Cer is unknown. We investigated the role of the configuration at C-3 of CerNS and CerNdS in the organization and permeability of model Skin Lipid membranes. Unnatural l-threo-CerNS and l-threo-CerNdS with 24-C acyl chains were synthesized and, along with their natural d-erythro-isomers, incorporated into membranes composed of major stratum corneum Lipids (Cer, free fatty acids, cholesterol, and cholesteryl sulfate). The membrane microstructure was investigated by X-ray powder diffraction and infrared spectroscopy, including deuterated free fatty acids. Inversion of the C-3 configuration in CerNS and CerNdS increased phase transition temperatures, had no significant effects on lamellar phases, but also decreased the proportion of orthorhombic packing and decreased Lipid mixing in the model membranes. These changes in membrane organization resulted in membrane permeabilities that ranged from unchanged to 5-fold higher (depending on the permeability markers, namely, water loss, electrical impedance, flux of theophylline, and flux of indomethacin) compared to membranes with natural CerNS/NdS isomers. Thus, the physiological d-erythro stereochemistry of Skin Cer and dihydroCer appears to be essential for their correct barrier function.
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Phytosphingosine, sphingosine and dihydrosphingosine ceramides in model Skin Lipid membranes: permeability and biophysics
Biochimica et Biophysica Acta, 2017Co-Authors: Barbora Školová, Lukas Opalka, Andrej Kovacik, Ondřej Tesař, Kateřina VavrovaAbstract:Ceramides based on phytosphingosine, sphingosine and dihydrosphingosine are essential constituents of the Skin Lipid barrier that protects the body from excessive water loss. The roles of the individual ceramide subclasses in regulating Skin permeability and the reasons for C4-hydroxylation of these sphingoLipids are not completely understood. We investigated the chain length-dependent effects of dihydroceramides, sphingosine ceramides (with C4-unsaturation) and phytoceramides (with C4-hydroxyl) on the permeability, Lipid organization and thermotropic behavior of model stratum corneum Lipid membranes composed of ceramide/lignoceric acid/cholesterol/cholesteryl sulfate. Phytoceramides with very long C24 acyl chains increased the permeability of the model Lipid membranes compared to dihydroceramides or sphingosine ceramides with the same chain lengths. Either unsaturation or C4-hydroxylation of dihydroceramides induced chain length-dependent increases in membrane permeability. Infrared spectroscopy showed that C4-hydroxylation of the sphingoid base decreased the relative ratio of orthorhombic chain packing in the membrane and lowered the miscibility of C24 phytoceramide with lignoceric acid. The phase separation in phytoceramide membranes was confirmed by X-ray diffraction. In contrast, phytoceramides formed strong hydrogen bonds and highly thermostable domains. Thus, the large heterogeneity in ceramide structures and in their aggregation mechanisms may confer resistance towards the heterogeneous external stressors that are constantly faced by the Skin barrier.
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omega o acylceramides in Skin Lipid membranes effects of concentration sphingoid base and model complexity on microstructure and permeability
Langmuir, 2016Co-Authors: Lukas Opalka, Andrej Kovacik, Jaroslav Maixner, Kateřina VavrovaAbstract:Omega-O-acylceramides (acylCer), a subclass of sphingoLipids with an ultralong N-acyl chain (from 20 to 38 carbons, most usually 30 and 32 carbons), are crucial components of the Skin permeability barrier. AcylCer are involved in the formation of the long periodicity lamellar phase (LPP, 12–13 nm), which is essential for preventing water loss from the body. Lower levels of acylCer and LPP accompany Skin diseases, such as atopic dermatitis, lamellar ichthyosis, and psoriasis. We studied how the concentration and structure of acylCer influence the organization and permeability barrier properties of model Lipid membranes. For simple model membranes composed of the sphingosine-containing acylCer (EOS), N-lignoceroyl sphingosine, lignoceric acid, cholesterol (Chol), and cholesteryl sulfate (CholS), the LPP formed at 10% Cer EOS (of the total Cer) and the short periodicity phase disappeared at 30% Cer EOS. Surprisingly, membranes with the LPP had higher permeabilities than the control membrane without acylCer. ...
James M. Ntambi - One of the best experts on this subject based on the ideXlab platform.
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A Discussion on the Relationship between Skin Lipid Metabolism and Whole-Body Glucose and Lipid Metabolism: Systematic Review.
Journal of cell signaling, 2018Co-Authors: Sabrina N Dumas, James M. NtambiAbstract:The obesity epidemic is a costly public health crisis that is not improving. In addition to the stigma and discomfort associated with carrying extra weight (at the expense of range of movement), obesity also goes hand-in-hand with co-morbidities like fatty liver disease, diabetes, cardiovascular disease, and increased risk of some forms of cancer. Currently there are no long-lasting treatments for obesity other than diet and exercise, which are not feasible for many populations that may not be equipped with the resources and/or support needed to lead a healthy lifestyle. Although there have been some pharmacological breakthroughs for treating obesity, each FDA-approved drug comes with unpleasant side-effects that make adherence unlikely. As a result, alternate approaches are necessary. In this review, we outline the relationship between Skin Lipid metabolism and whole-body glucose and Lipid metabolism. Specifically, by summarizing studies that employed mice that were genetically modified to interrupt Lipid metabolism in the Skin. As a result, we propose that Skin might be an overlooked, but viable target for combating obesity.
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Skin specific deletion of stearoyl coa desaturase 1 alters Skin Lipid composition and protects mice from high fat diet induced obesity
Journal of Biological Chemistry, 2009Co-Authors: Harini Sampath, Matthew T Flowers, Chad M Paton, Ruth Sullivan, Minghui Zhao, James M. NtambiAbstract:Abstract Stearoyl-CoA desaturase-1 (SCD1) catalyzes the synthesis of monounsaturated fatty acids and is an important regulator of whole body energy homeostasis. Severe cutaneous changes in mice globally deficient in SCD1 also indicate a role for SCD1 in maintaining Skin Lipids. We have generated mice with a Skin-specific deletion of SCD1 (SKO) and report here that SKO mice display marked sebaceous gland hypoplasia and depletion of sebaceous Lipids. In addition, SKO mice have significantly increased energy expenditure and are protected from high fat diet-induced obesity, thereby recapitulating the hypermetabolic phenotype of global SCD1 deficiency. Genes of fat oxidation, lipolysis, and thermogenesis, including uncoupling proteins and peroxisome proliferator-activated receptor-γ co-activator-1α, are up-regulated in peripheral tissues of SKO mice. However, unlike mice globally deficient in SCD1, SKO mice have an intact hepatic lipogenic response to acute high carbohydrate feeding. Despite increased basal thermogenesis, SKO mice display severe cold intolerance because of rapid depletion of fuel substrates, including hepatic glycogen, to maintain core body temperature. These data collectively indicate that SKO mice have increased cold perception because of loss of insulating factors in the Skin. This results in up-regulation of thermogenic processes for temperature maintenance at the expense of fuel economy, illustrating cross-talk between the Skin and peripheral tissues in maintaining energy homeostasis.
Gert S. Gooris - One of the best experts on this subject based on the ideXlab platform.
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free fatty acids chain length distribution affects the permeability of Skin Lipid model membranes
Biochimica et Biophysica Acta, 2016Co-Authors: Masayuki Uchiyama, Gert S. Gooris, Masashi Oguri, E H Mojumdar, Joke A. BouwstraAbstract:Abstract The Lipid matrix in the stratum corneum (SC) plays an important role in the barrier function of the Skin. The main Lipid classes in this Lipid matrix are ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs). The aim of this study was to determine whether a variation in CER subclass composition and chain length distribution of FFAs affect the permeability of this matrix. To examine this, we make use of Lipid model membranes, referred to as stratum corneum substitute (SCS). We prepared SCS containing i) single CER subclass with either a single FFA or a mixture of FFAs and CHOL, or ii) a mixture of various CER subclasses with either a single FFA or a mixture of FFAs and CHOL. In vitro permeation studies were performed using ethyl-p-aminobenzoic acid (E-PABA) as a model drug. The flux of E-PABA across the SCS containing the mixture of FFAs was higher than that across the SCS containing a single FA with a chain length of 24 C atoms (FA C24), while the E-PABA flux was not effected by the CER composition. To select the underlying factors for the changes in permeability, the SCSs were examined by Fourier transform infrared spectroscopy (FTIR) and Small angle X-ray scattering (SAXS). All Lipid models demonstrated a similar phase behavior. However, when focusing on the conformational ordering of the individual FFA chains, the shorter chain FFA (with a chain length of 16, 18 or 20 C atoms forming only 11 m/m% of the total FFA level) had a higher conformational disordering, while the conformational ordering of the chains of the CER and FA C24 and FA C22 hardly did not change irrespective of the composition of the SCS. In conclusion, the conformational mobility of the short chain FFAs present only at low levels in the model SC Lipid membranes has a great impact on the permeability of E-PABA.
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the role of ceramide chain length distribution on the barrier properties of the Skin Lipid membranes
Biochimica et Biophysica Acta, 2014Co-Authors: E H Mojumdar, Gert S. Gooris, Z Kariman, L Van Kerckhove, Joke A. BouwstraAbstract:Abstract The Skin barrier function is provided by the stratum corneum (SC). The Lipids in the SC are composed of three Lipid classes: ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs) which form two crystalline lamellar structures. In the present study, we investigate the effect of CER chain length distribution on the barrier properties of model Lipid membranes mimicking the Lipid composition and organization of SC. The membranes were prepared with either isolated pig CERs (PCERs) or synthetic CERs. While PCERs have a wide chain length distribution, the synthetic CERs are quite uniform in chain length. The barrier properties were examined by means of permeation studies using hydrocortisone as a model drug. Our studies revealed a reduced barrier in Lipid membranes prepared with PCERs compared to synthetic CERs. Additional studies revealed that a wider chain length distribution of PCERs results in an enhanced hexagonal packing and increased conformational disordering of the Lipid tails compared to synthetic CERs, while the lamellar phases did not change. This demonstrates that the chain length distribution affects the Lipid barrier by reducing the Lipid ordering and density within the Lipid lamellae. In subsequent studies, the effect of increased levels of FFAs or CERs with a long acyl chain in the PCERs membranes was also studied. These changes in Lipid composition enhanced the level of orthorhombic packing, reduced the conformational disordering and increased the barrier of the Lipid membranes. In conclusion, the CER chain length distribution is an important key factor for maintaining a proper barrier.
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ceramides in the Skin Lipid membranes length matters
Langmuir, 2013Co-Authors: Barbora Školová, Joke A. Bouwstra, Gert S. Gooris, Barbora Janůsova, Jarmila Zbytovska, P Slepicka, Pavel Berka, Karel Palat, Alexandr Hrabalek, Kateřina VavrovaAbstract:Ceramides are essential constituents of the Skin barrier that allow humans to live on dry land. Reduced levels of ceramides have been associated with Skin diseases, e.g., atopic dermatitis. However, the structural requirements and mechanisms of action of ceramides are not fully understood. Here, we report the effects of ceramide acyl chain length on the permeabilities and biophysics of Lipid membranes composed of ceramides (or free sphingosine), fatty acids, cholesterol, and cholesterol sulfate. Short-chain ceramides increased the permeability of the Lipid membranes compared to a long-chain ceramide with maxima at 4–6 carbons in the acyl. By a combination of differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, Langmuir monolayers, and atomic force microscopy, we found that the reason for this effect in short ceramides was a lower proportion of tight orthorhombic packing and phase separation of continuous short ceramide-enriched domains with shorter lamellar period...
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Skin Lipid organization, composition and barrier function
International Journal of Cosmetic Science, 2008Co-Authors: Joke A. Bouwstra, Gert S. Gooris, Maria PonecAbstract:Citation: IFSCC Magazine, 10 (2007) (4) 297–307 The primary function of the Skin is to act as a barrier against unwanted influences from the environment and to protect the body from water loss. The barrier function of the Skin is located in the superficial layer of the Skin, the stratum corneum. The stratum corneum consists of dead cells filled with keratin and water, the corneocytes, embedded in Lipid regions. As the Lipid regions are the only continuous structure in the stratum corneum, they are considered to be very important for the Skin barrier function. The main Lipid classes are ceramides, cholesterol and free fatty acids. In this paper the Lipid organization in human stratum corneum is reviewed. In addition, the role the various Lipid classes play in Lipid organization is discussed using mixtures prepared from either native human ceramides or synthetic ceramides. Finally, a model is described which allows study of the relation between Lipid composition, organization and barrier function. This model is referred to as the stratum corneum substitute. Keywords: ceramides, FTIR, Lipid organization, stratum corneum, X-ray diffraction
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barrier characteristics of different human Skin types investigated with x ray diffraction Lipid analysis and electron microscopy imaging
Journal of Investigative Dermatology, 2000Co-Authors: Volker Schreiner, Gert S. Gooris, Stephan Pfeiffer, Ghita Lanzendorfer, Horst Wenck, Walter Diembeck, E Proksch, Joke A. BouwstraAbstract:The stratum corneum requires ceramides, cholesterol, and fatty acids to provide the cutaneous permeability barrier. The Lipids are organized in intercellular membranes exhibiting short- and long-periodicity lamellar phases. In recent years, the phase behavior of barrier Lipid mixtures has been studied in vitro . The relationship of human stratum corneum Lipid composition to membrane organization in vivo , however, has not been clearly established. Furthermore, the special function of the different ceramide species in the stratum corneum is largely unknown. We examined Lipid organization and composition of stratum corneum sheets from different subtypes of healthy human Skin (normal, dry, and aged Skin). Lipid organization was investigated using X-ray diffraction and demonstrated that the 4.4 nm peak attributed to the long periodicity phase was frequently missing for Skin with a low Cer(EOS)/Cer total ratio, indicating an important part for Cer(EOS), which contains ω-hydroxy fatty acid (O) ester-linked to linoleic acid (E) and amide-linked to sphingosine (S). A deficiency in the 4.4 nm peak was predominantly observed in young dry Skin. In one case of aged Skin, however, and less often in young normal Skin this peak was also missing. Furthermore, the ceramide composition of samples without the 4.4 nm peak showed a deficiency of Cer(EOH), which contains 6-hydroxy-4-sphingenine (H), and an increase in Cer(NS) and Cer(AS), which contain nonhydroxy (N) or α-hydroxy fatty acids (A). In addition, a 3.4 nm peak attributed to crystalline cholesterol occurred in most cases of aged and dry Skin, but was not observed in young normal Skin. Our results do not indicate a definite pattern of correlation between Lipid organization and types of human Skin. They demonstrate, however, that Cer(EOS) and Cer(EOH) are key elements for the molecular organization of the long periodicity lamellar phase in the human stratum corneum.