The structure, function, and importance of ceramides in skin and their use as therapeutic agents in skin-care products

Ceramides (CERs) are epidermal lipids that are important for skin barrier function. Much research has been devoted to identifying the numerous CERs found in human skin and their function. Alterations in CER content are associated with a number of skin diseases such as atopic dermatitis. Newer formulations of skin-care products have incorporated CERs into their formulations with the goal of exogenously applying CERs to help skin barrier function. CERs are a complex class of molecules and because of their growing ubiquity in skin-care products, a clear understanding of their role in skin and use in skin-care products is essential for clinicians treating patients with skin diseases. This review provides an overview of the structure, function, and importance of skin CERs in diseased skin and how CERs are being used in skin-care products to improve or restore skin barrier function.

Atopic dermatitis, and the role for a ceramide-dominant, physiologic lipid-based barrier repair emulsion

Over the last half century, and especially over the last 15 years, understanding of the structure and function of the stratum corneum has evolved tremendously. Once conceptualized as an inactive film formed by lifeless, disintegrating keratinocytes, the stratum corneum is now recognized as a viable, functional structure that plays an important role in maintaining skin health and possibly mediating cutaneous diseases. Researchers and clinicians have also come to realize that the barrier functions not only to prevent the entry of exogenous factors, such as irritants or allergens, but that it also can mediate disease. We had already realized that dysfunction of the barrier may itself directly contribute to the pathogenesis of skin diseases, notably atopic dermatitis. More specifically, evidence shows that epidermal barrier dysfunction is likely to be a precursor of cutaneous inflammation.

Improved high-fat diet-induced glucose intolerance by an oral administration of phytosphingosine

We have previously reported that phytoceramide and phytosphingosine (PHS) stimulated the transcriptional activity of peroxisome proliferator-activated receptor γ (PPARγ) in cells. PPARγ is a therapeutic target for type 2 diabetes. We found in this study that an oral administration of PHS improved diet-induced glucose intolerance in mice. Since PHS is highly expressed in yeast, PHS in fermented foods may improve diabetes.

Trojan-horse nanotube on-command intracellular drug delivery

A major challenge to nanomaterial-based medicine is the ability to release drugs on-command. Here, we describe an innovative drug delivery system based on carbon nanotubes (CNTs), in which compounds can be released inside cells from within the nanotube "on-command" by inductive heating with an external alternating current or pulsed magnetic field. Without inductive heating the drug remains safely inside the CNTs, showing no toxicity in cell viability tests. Similar to the "Trojan-Horse" in function, we demonstrate the delivery of a combination of chemotherapeutic agents with low aqueous solubility, paclitaxel (Taxol), and C6-ceramide, to multidrug resistant pancreatic cancer cells. Nanotube encapsulation permitted the drugs to be used at a 100-fold lower concentration compared to exogenous treatment yet achieve a comparable ~70% cancer kill rate.

Adjunctive use of a facial moisturizer SPF 30 containing ceramide precursor improves tolerability of topical tretinoin 0.05%: a randomized, investigator-blinded, split-face study

OBJECTIVES

To assess the benefit of adjunctive use of a SPF 30 moisturizing lotion in reducing local side effects associated with atopical tretinoin cream.

METHODS

This was a randomized, investigator/evaluator-blinded, split-face comparison in subjects with healthy skin. Subjects applied tretinoin cream 0.05% once daily to the whole face and Cetaphil 174; Dermacontrol Moisturizer (CDM) once daily to one side of the face based on randomization. Tolerability, perference and skin hydration were evaluated at each week, and a cosmetic acceptability questionnaire regarding CDM was completed at the end of the study.

RESULTS

The majority (about 83% to 86%) of subjects experienced skin irritations on both sides of their face, though predominantly mild for the CDM + tretinoin treated side. Tolerability preferences favored the CDM+tretinoin sides. Adjunctive use of CDM with a topical tretinoin cream improves tolerance of the treatment.

A look at epidermal barrier function in atopic dermatitis: physiologic lipid replacement and the role of ceramides

This review summarizes and discusses the role and efficacy of moisturizers, particularly the more recently introduced ceramide-based formulations, in the skin care regimen of patients with both active and quiescent atopic dermatitis (AD). It is now well established that a complex interplay of environmental and genetic factors are responsible for disease onset and chronicity. Indeed, several novel genetic mechanisms have been recently discovered to be associated with AD pathogenesis. Moreover, it is increasingly recognized that the epidermal barrier plays a critical role in the initiation, perpetuation, and exacerbation of AD. The skin of patients with AD harbors several defects in epidermal barrier function, including filaggrin and ceramides. An improved understanding of these etiopathogenic factors has led to the development of topical ceramide-dominant moisturizers to replace the deficient molecules and re-establish the integrity of barrier defenses. Some of these products have demonstrated efficacy in the treatment of adult and childhood AD that are similar to mid-potency topical steroids. More importantly, they have been shown to be safe with very few associated side-effects. We recommend the addition of such new agents as both the first step of treatment and in the maintenance of clinically quiescent skin of patients with AD.

Efficacy and safety of a ceramide containing moisturizer followed by fixed-dose clindamycin phosphate 1.2%/benzoyl peroxide 2.5% gel in the morning in combination with a ceramide containing moisturizer followed by tretinoin 0.05% gel in the evening for the treatment of facial acne vulgaris

Combination therapy addressing multiple pathogenic factors should be used to achieve optimal outcomes in treating acne. The following study demonstrated both safety and efficacy of fixed-dose clindamycin phosphate 1.2%/benzoyl peroxide 2.5% in the morning with micronized tretinoin 0.05% gel in the evening. Both products were applied to the skin following the use of a ceramide containing moisturizing lotion.

Bilateral comparison study of pimecrolimus cream 1% and a ceramide-hyaluronic acid emollient foam in the treatment of patients with atopic dermatitis

Topical corticosteroids have been the mainstay of treatment for atopic dermatitis (AD) over the last decade, especially in the setting of acute flares. However, heavy and prolonged use of topical corticosteroid is undesirable as it is associated with side effects such as, skin atrophy, telangiectasia, striae, steroid-induced dermatoses, rosacea, acne exacerbation, and in some severe and rare cases, systemic effects such as hypothalamic-pituitary-adrenal axis suppression, growth retardation and ocular problems. Non-steroidal ant-inflammatory agents specific for the treatment of AD (topical calcineurin inhibitors, or TCIs) are now available and they are a viable alternative to topical corticosteroids in treating dermatitis of the face, neck, eyelids, and intertriginous areas where there is a greater risk of the steroid-induced side effects. More recently, medical device emollients have entered the marketplace. These medical devices provide, but are not limited to, anti-oxidant, anti-protease, anti-inflammatory activity, and aid in restoring the natural balance of lipids, which is one of the causes of the epidermal abnormalities seen with AD. The present study evaluated the short-term effectiveness and appeal of a non-steroidal medicated device foam as compared to pimecrolimus cream 1% in the treatment of AD within a wide age group of subjects with active disease at baseline. In this study, both pimecrolimus and the medical device foam exhibited efficacy in mild-to-moderate AD. Primary efficacy was measured by IGA. After four weeks of treatment with the medical device foam, 82% of target lesions were scored "clear" (0) or "almost clear" (1) compared to 71% of target lesions under the pimecrolimus arm. This study confirmed that pimecrolimus cream 1% and the medical device foam work well in the treatment of AD in both adults and children with no associated adverse effects.

An over-the-counter moisturizer is as clinically effective as, and more cost-effective than, prescription barrier creams in the treatment of children with mild-to-moderate atopic dermatitis: a randomized, controlled trial

BACKGROUND

Atopic dermatitis (AD) is a prevalent skin disorder with significant cost of treatment. Several prescription device moisturizers have been approved by the FDA to treat AD but are significantly more expensive than well-crafted over-the-counter (OTC) moisturizers. No studies have been performed to compare both the clinical efficacy and cost-efficacy of these prescription devices to OTC moisturizers.

PURPOSE

The purpose of this study is to compare the clinical efficacy and cost-efficacy of a glycyrrhetinic acid-containing barrier repair cream (BRC-Gly, Atopiclair®), a ceramide-dominant barrier repair cream (BRC-Cer, EpiCeram®) and an OTC petroleum-based skin protectant moisturizer (OTC-Pet, Aquaphor Healing Ointment®) as monotherapy for mild-to-moderate AD in children.

METHODS

Thirty-nine patients, age 2-17 years, with mild-to-moderate AD were randomized 1:1:1 to receive one of three treatments-BRC-Gly, BRC-Cer or OTC-Pet-with instructions to apply the treatment three times daily for three weeks. Disease severity and improvement was assessed at baseline and on days 7 and 21.

RESULTS

No statistically significant difference for any efficacy assessment was found between the three groups at each time point. The OTC-Pet was found to be at least 47 times more cost-effective than BRC-Gly or BRC-Cer.

LIMITATIONS

The relatively small sample size of 39 subjects was not sufficient to establish OTC-Pet as superior treatment in AD.

CONCLUSIONS

OTC-Pet is as effective in treating mild-to-moderate AD as both BRC-Gly and BRC-Cer and is at least 47 times more cost-effective.

NAME OF REGISTRY

II-AF-ATD-Aquaphor, Comparing the Efficacy and Cost-Effectiveness of Aquaphor to Atopiclair and EpiCeram in Children with Mild to Moderate Atopic Dermatitis. REGISTRATION IDENTIFIER: NCT01093469.

C6-ceramide synergistically potentiates the anti-tumor effects of histone deacetylase inhibitors via AKT dephosphorylation and α-tubulin hyperacetylation both in vitro and in vivo

Histone deacetylase inhibitors (HDACIs) have shown promising anti-tumor effects for a variety of malignancies, however, many tumors are reportedly resistant to them. In this study, we made a novel discovery that co-administration of HDACIs (Trichostatin A (TSA) and others) and exogenous cell-permeable short-chain ceramide (C6) results in striking increase in cancer cell death and apoptosis in multiple cancer cells. These events are associated with perturbations in diverse cell signaling pathways, including inactivation of Akt/mTOR and increase in α-tubulin acetylation (both in vivo and in vitro). TSA interacts in a highly synergistic manner with C6-ceramide to disrupt HDAC6/protein phosphatase 1 (PP1)/tubulin complex, to induce α-tubulin hyperacetylation, and to release and activate PP1, which then leads to AKT dephosphorylation and eventually causes cancer cell death. Interestingly, TSA itself results in short-term ceramide accumulation, which as a result of metabolic (glycosylation) removal, does not result in evident increase of cancer cell death. However, adding C6-ceramide led to a very pronounced increase in ceramide level and marked increase in cell death. Importantly, the effective synergistic anti-tumor activity of TSA plus C6-ceramide is also seen in in vivo mice xenograft pancreatic and ovarian cancer models, indicating that this regimen (HDACI plus C6-ceramide) may represent a more effective form of therapy against pancreatic and ovarian carcinoma.

Skin efficacy of liposomes composed of internal wool lipids rich in ceramides

Ceramides from intercellular lipids of skin stratum corneum are known to play an essential role in maintaining and structuring the lipid barrier of the skin. Internal wool lipids (IWL), which are also rich in ceramides, have a composition similar to that of the stratum corneum lipids. IWL extracted with chloroform/methanol azeotrope at the laboratory scale have been shown to be capable of forming liposomes with a stable bilayer structure. Furthermore, topical application of these IWL liposomes on intact and compromised skin has been demonstrated to improve barrier skin properties.In this study we evaluated the effect on human skin repair of different IWL extract compositions obtained by two extraction methodologies. The formation and characteristics of the liposomes prepared were greatly influenced by the IWL composition, primarily the sterol sulfate content. The IWL liposomes improved skin barrier integrity and increased skin hydration when applied onto intact skin. These improvements were slightly enhanced in the case of IWL liposomes that were richer in polar lipids.

Changes of antimicrobial peptides and transepidermal water loss after topical application of tacrolimus and ceramide-dominant emollient in patients with atopic dermatitis

Increased transepidermal water loss (TEWL) and downregulated antimicrobial peptides (AMPs) are observed in patients with atopic dermatitis (AD). Tacrolimus and ceramide-dominant emollients are effective in the treatment of AD by preventing the production of inflammatory cytokines and by correcting skin barrier dysfunctions, respectively. Present study was designed to investigate the relationship between antimicrobial and barrier factors by measuring the changes of AMPs and TEWL after topical application of tacrolimus and ceramide-dominant emollient in the patients with AD. A total of three patients with AD were treated with tacrolimus in one lesion and ceramide-dominant emollient in another lesion for 4 weeks. RT-PCR and western blotting revealed that the mRNA and protein expression levels of hBD-2 and LL-37 were increased on the both study sites. Immunohistochemical analysis showed significant increase of AMPs and IL-1alpha, while, IL-4 was decreased on the both study sites. The mean changes of TEWL and AMPs showed no statistical difference between both sites. Tacrolimus and ceramide-dominant emollient influence on both TEWL and AMPs expression in patients with AD, namely they have similar effects on both of the two. This study shows that restoration of permeability barrier function is accompanied by the concomitant improvement of antimicrobial defense in patients with AD.

Liposomes for drug delivery to mitochondria

Efficacy of therapeutically active drugs known to act on intracellular targets can be enhanced by specific delivery to the site of action. Triphenylphosphonium cations can be used to create subcellular targeted liposomes that efficiently deliver drugs to mitochondria, thus enhancing their therapeutic action.

Efficacy of a lipid-based barrier repair formulation in moderate-to-severe pediatric atopic dermatitis

OBJECTIVES

The authors assessed the efficacy of a ceramide-dominant, triple-lipid barrier repair formulation (EpiCeram), which designed to correct the lipid-biochemical abnormalities in atopic dermatitis (AD) in comparison to fluticasone propionate cream.

METHODS

In a five-center, investigator-blinded, randomized trial, EpiCeram was compared to fluticasone (Cutivate) cream in 121 patients with moderate-to-severe AD. Primary outcome measures were: 1) reduction in disease severity, assessed as SCORAD (Severity Scoring for Atopic Dermatitis) scores; 2) improvement in pruritus; and 3) improvements in sleep habits.

RESULTS

EpiCeram reduced clinical disease severity, decreased pruritus and improved sleep habits both 14 and 28 days after initiation of therapy. Although the fluticasone-treated group showed significantly greater improvement at 14 days, SCORAD, pruritus and sleep habit scores for EpiCeram did not differ significantly from the fluticasone-treated group by 28 days.

CONCLUSION

The ceramide-dominant, physiological-lipid based formulation could represent an effective stand-alone or ancillary therapy for many pediatric patients with AD.

In vitro and in vivo anti-angiogenic activities and inhibition of hormone-dependent and -independent breast cancer cells by ceramide methylaminoethylphosphonate

Ceramide methylaminoethylphosphonate (CMAEPn) was isolated from eastern oyster ( Crassostrea virginica ) and screened against in vitro and in vivo angiogenesis and against MCF-7 and MDA-MB-435s breast cancer cell lines. In vitro angiogenesis was evaluated by the vascular endothelial growth factor (VEGF)-induced human umbilical vein endothelial cell (HUVEC) tube formation assay. MCF-7 and MDA-MB-435s cell viability was evaluated by the CellTiter 96 AQ(ueous) One Solution Cell Proliferation assay. Apoptosis was evaluated by the caspase-9 assay, autophagy by acridine orange staining and beclin-1 level. Our study indicates that CMAEPn at 50 microM inhibited VEGF-induced tube formation by HUVEC. The viability of MCF-7 and MDA-MB-435s breast cancer cells exposed to 125 microM CMAEPn for 48 h was reduced to 76 and 85%, respectively. The viability of MCF-7 and MDA-MB-435s cells exposed to 250 microM CMAEPn for 48 h under the same conditions was reduced to 38 and 45%, respectively. CMAEPn at 125 microM inhibited VEGF-induced MDA-MB-435s cell migration and invasion. CMAEPn at 125 microM also decreased VEGF, EGF levels in the conditioned media, PI3K, IkappaB phosphorylation and degradation in the cytoplasmic extracts, and NFkappaB nuclear translocation. Both acridine orange staining and beclin-1 indicated autophagic cell death in MCF-7 and MDA-MB-435s cells, respectively. In vivo, CMAEPn at 30 mg/kg body weight inhibited bFGF-induced angiogenesis and caused a 57% reduction in hemoglobin levels in the matrigel plug assay within 7 days. This is the first report on CMAEPn-inhibited angiogenesis both in vitro and in vivo.

Inhibition of skin inflammation and atopic dermatitis by topical application of a novel ceramide derivative, K112PC-5, in mice

PC-9S (N-Ethanol-2-mirystyl-3-oxo-stearamide) is a synthetic ceramide and has been known to be effective in atopic and psoriatic patients. K112PC-5 (2-Acetyl-N-(1,3-dihydroxyisopropyl)-tetradecanamide) is a novel ceramide derivative of PC-9S. In the present study, we examined the effect of K112PC-5 on macrophage and T lymphocyte function in primary macrophages and splenocytes, respectively, as well as the effect of topical application of K112PC-5 on skin inflammation and atopic dermatitis (AD) in mouse models. K112PC-5 inhibited lipopolysaccharide-induced nitrite generation in mouse peritoneal macrophages in a dose-dependent manner. However, K112PC-5 did not affect concanavalin A-induced proliferation, interleukin (IL)-2 secretion and IL-4 secretion in mouse splenocytes. In addition, K112PC-5 significantly suppressed the increase in phorbol ester-induced ear thickness in BALB/c mice. Further study demonstrated that topical application of K112PC-5 also inhibited AD induced by extracts of dust mites, Dermatophagoides pteronyssinus and Dermatophagoides farinae, in NC/Nga mice. Taken together, these results showed that K112PC-5 exerted an anti-inflammatory effect both in vitro and in vivo and proved to be beneficial in an animal model of AD. Our results suggest that K112PC-5 might be beneficial as a topical agent for the treatment of AD.

Biodistribution and pharmacokinetic analysis of Paclitaxel and ceramide administered in multifunctional polymer-blend nanoparticles in drug resistant breast cancer model

In this study, we have investigated the biodistribution and pharmacokinetic analysis of paclitaxel (PTX) and the apoptotic signaling molecule, C6-ceramide (CER), when administered in a multifunctional polymer-blend nanoparticle formulation to female nude mice bearing an orthotopic drug sensitive MCF7 and multidrug resistant MCF7 TR (MDR-1 positive) human breast adenocarcinoma. A polymer-blend nanoparticle system was engineered to incorporate temporally controlled sequential release of the combination drug payload. Hereby, PTX was encapsulated in the pH-responsive rapid releasing polymer, poly(beta-amino ester) (PbAE), while CER was present in the slow releasing polymer, poly(D,L-lactide-co-glycolide) (PLGA) within these blend nanoparticles. When particle formulations were administered intravenously to MCF7 and MCF7 TR tumor bearing mice, higher concentrations of PTX were found in the blood due to longer retention time and an enhanced tumor accumulation relative to administration of free drug. In addition, the PLGA/PbAE blend nanoparticles were effective in enhancing the residence time of both drugs at the tumor site by reducing systemic clearance. Overall, these results are highly encouraging for development of multifunctional polymer-blend nanoparticle formulations that can be used for temporal-controlled administration of two drugs from a single formulation.

The effect of ceramide-containing skin care products on eczema resolution duration

Eczema is a common dermatologic condition that affects children as well as adults and is related to a defective skin barrier, which is most commonly caused by damage to the intercellular lipids from improper selection of skin cleansers and moisturizers. A new concept in skin care is the incorporation of ceramides into therapeutic cleansers and moisturizers. Ceramides are important components of the intercellular lipids that are necessary to link the protein-rich corneocytes into a waterproof barrier that is capable of protecting the underlying skin tissues and regulating body homeostasis. This study evaluated the effect of both a multilamellar vesicular emulsion (MVE) ceramide-containing liquid cleanser and moisturizing cream plus fluocinonide cream 0.05% compared with a bar cleanser plus fluocinonide cream 0.05% in the treatment of mild to moderate eczema. The addition of an MVE ceramide-containing liquid cleanser and moisturizing cream to a high-potency corticosteroid enhanced the treatment outcome of mild to moderate eczema compared with the use of a bar cleanser and high-potency corticosteroid in reducing disease duration, time to disease clearance, and symptoms. Thus, skin care product selection can have an important clinical effect on the clearance of mild to moderate eczema.

Paclitaxel and ceramide co-administration in biodegradable polymeric nanoparticulate delivery system to overcome drug resistance in ovarian cancer

The objective of this study was to overcome drug resistance upon systemic administration of combination paclitaxel (PTX) and the apoptotic signaling molecule C(6)-ceramide (CER) in biodegradable poly(ethylene oxide)-modified poly(epsilon-caprolactone (PEO-PCL) nanoparticles. Subcutaneous sensitive (wild-type) and multidrug resistant (MDR-1 positive) SKOV-3 human ovarian adenocarcinoma xenografts were established in female Nu/Nu mice. PTX and CER were administered intravenously either as a single agent or in combination in aqueous solution and in PEO-PCL nanoparticles to the tumor-bearing mice. There was significant (p< 0.05) tumor growth suppression in both wild-type SKOV-3 and multidrug resistant SKOV-3(TR) models upon single dose co-administration of PTX (20 mg/kg) and CER (100 mg/kg) in nanoparticle formulations as compared to the individual agents and administration in aqueous solutions. For instance, in SKOV-3 wild-type model, more than 4.3-fold increase (p < 0.05) in tumor growth delay and 3.6-fold (p < 0.05) increase in tumor volume doubling time (DT) were observed with the combination treatment in nanoparticles as compared to untreated animals. Similarly, 3-fold increase (p < 0.05) in tumor growth delay and tumor volume DT was observed in SKOV-3(TR) model. Body weight changes and blood cells counts were used as measures of safety and, except for an increase in platelet counts (p < 0.05) in PTX + CER treated animals, there was no difference between various treatment strategies. The results of this study show that combination of PTX and CER in biodegradable polymeric nanoparticles can serve as a very effective therapeutic strategy to overcome drug resistance in ovarian cancer.

Ceramide-induced cell death in lens epithelial cells

PURPOSE

To determine whether ceramide treatment contributes to reduced cell viability, increased apoptosis, caspase activation, and reactive oxygen species generation in lens epithelial cells.

METHODS

Cell viability was determined by the 3-(4,5-dimethylthiozol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptotic cell death was determined by 4,6 diamidino-2-phenylindole (DAPI) nuclear staining. Quantitative DNA fragmentation was determined by specific determination of cytosolic mononucleosomes and oligonucleosome-bound DNA. Caspase-3/7 activation was determined by using the Apo-ONE Assay. Detection of reactive oxygen species was achieved by a carboxy-2,7-dichlorofluorescein diacetate (carboxy-H2DCFDA) staining method and lipid peroxidation assay.

RESULTS

C2-ceramide and C6-ceramide reduced primary bovine lens epithelial cell and human lens epithelial cell survival in a dose- and time-dependent manner. The effect of ceramide on cell viability was specific since C2-dihydroceramide, a chemically similar ceramide lacking four to five double-bonds, did not adversely affect lens epithelial cell viability. Release of endogenous natural ceramides by treatment of lens epithelial cells with bacterial sphingomyelinase reduced cell viability. Ceramide-induced apoptosis in lens epithelial cells was determined by nuclear appearance and DNA fragmentation. Apoptosis was induced by exogenous C2-ceramide in a dose-dependent and time-dependent manner and ceramide-mediated apoptosis of lens epithelial cells was associated with caspase-3/7 activation. C2-ceramide treatment resulted in reactive oxygen species generation.

CONCLUSIONS

These results suggest that ceramide reduced cell viability and increased apoptosis in a dose-dependent and time-dependent manner in lens epithelial cells. Ceramide-induced oxidative stress suggests that age-related cataracts may be modulated by ceramide levels in the lens.

Potassium loss is involved in tobacco cell death induced by palmitoleic acid and ceramide

Tobacco cell death induced by palmitoleic acid (16:1), ceramide, and KCN was found to possess features associated with program cell death (PCD), including cell volume decrease, loss of membrane integrity, DNA damage, nuclear and plastid disorganization, and chromatin condensation. Cell volume decrease was found to be caused by loss of intracellular K(+). Ba(2+) was able to prevent the K(+) loss and it also protected the cells from death induced by 16:1 and ceramide but not KCN. The results suggest that K(+) loss is a critical step in plant PCD. The inability of Ba(2+) to prevent cell death was most likely due to its other effects of KCN, i.e., inhibition of cytochrome oxidase in the respiratory chain and generation of reactive oxygen species.

Scanning electron microscopy study on nanoemulsions and solid lipid nanoparticles containing high amounts of ceramides

Ceramides are the most important intercellular lipids of the stratum corneum, regulating the barrier function of the skin and participating as second signal messenger in stress-induced apoptosis. The high lipophilicity of ceramides presents a pharmacological problem. In order to overcome this problem two lipophilic delivery systems were used for the incorporation of the ceramides: (1) nanoemulsions (NE) and (2) solid lipid nanoparticles (SLN). The influence of the incorporation of ceramides on the particle shape, size and Polydispersity Index was investigated by photon correlation spectroscopy (PCS) and scanning electron microscopy (SEM). The results showed that NE can incorporate larger amounts of ceramides than SLN (up to 23.2% and 5% of lipid matrix, respectively) without any significant alteration on the morphology of the dispersed particles. The incorporation of higher amounts of ceramides into SLN, leads to anisometric platelet-like formations that are known to be caused by the transition of triglycerides from alpha- to beta-mesomorph. The results of this study can be useful for the design of appropriate delivery systems and for further pharmacological evaluations.

Modulation of Intracellular Ceramide Using Polymeric Nanoparticles to Overcome Multidrug Resistance in Cancer

Although multidrug resistance (MDR) is known to develop through a variety of molecular mechanisms within the tumor cell, many tend to converge toward the alteration of apoptotic signaling. The enzyme glucosylceramide synthase (GCS), responsible for bioactivation of the proapoptotic mediator ceramide to a nonfunctional moiety glucosylceramide, is overexpressed in many MDR tumor types and has been implicated in cell survival in the presence of chemotherapy. The purpose of this study was to investigate the therapeutic strategy of coadministering ceramide with paclitaxel, a commonly used chemotherapeutic agent, in an attempt to restore apoptotic signaling and overcome MDR in the human ovarian cancer cell line SKOV3. Poly(ethylene oxide)-modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticles were used to encapsulate and deliver the therapeutic agents for enhanced efficacy. Results show that indeed the cotherapy eradicates the complete population of MDR cancer cells when they are treated at their IC(50) dose of paclitaxel. More interestingly, when the cotherapy was combined with the properties of nanoparticle drug delivery, the MDR cells can be resensitized to a dose of paclitaxel near the IC(50) of non-MDR (drug sensitive) cells, indicating a 100-fold increase in chemosensitization via this approach. Molecular analysis of activity verified the hypothesis that the efficacy of this therapeutic approach is indeed due to a restoration in apoptotic signaling, although the beneficial properties of PEO-PCL nanoparticle delivery seemed to enhance the therapeutic success even further, showing the promising potential for the clinical use of this therapeutic strategy to overcome MDR.

Enhanced ceramide-induced apoptosis in ceramide kinase overexpressing cells

We evaluated how increased levels of ceramide kinase (CerK) would impact the growth of COS-1 fibroblasts and RBL-2H3 basophils. The low CerK activity in these cells was strongly up-regulated upon recombinant expression of CerK. CerK-overexpressing COS-1 cells depended on higher concentrations of serum for their growth and displayed many filipodia. The two CerK-overexpressing cell lines were more sensitive to C2-ceramide-mediated apoptosis, and this correlated with the production of C2-ceramide-1-phosphate by CerK. This study indicates that ceramide kinase may participate in the control of cell growth, and establishes a novel assay that will be valuable for testing ceramide kinase inhibitors.

[Evaluation of skin-moisturizing effects of oral or percutaneous use of plant ceramides]

This study was undertaken to evaluate the assay performance of two methods for measuring the water-holding capacity of the skin: Skicon-200 and Tewameter which determine the water content in the stratum corneum and transepidermal water loss, respectively. Based on these findings, we studied the effects of newly developed skin moisturizers made of plant ceramides. The within-run as well as day-to-day reproducibility of the methods were both satisfactory. When rice-derived NIPPN ceramide RC was used topically for 3 weeks by 23 healthy volunteers, the water content in the stratum corneum of the leg was significantly increased to 141% of the baseline value in comparison with that after placebo use (111%) (p < 0.05), and the transepidermal water-loss was significantly suppressed to 23% of the baseline in comparison with that after placebo use (39%) (p < 0.01). When 20 mg or 40 mg/day of corn-derived NIPPN ceramide CP was given orally for 3 weeks, the water content in the stratum corneum of the leg was significantly increased to 290% and 394% of the baseline value, respectively, in comparison with that after placebo administration (141%) (p <0.05), and the transepidermal water loss was suppressed to 33 and 14% (p < 0.05) of the baseline values, respectively, in comparison with that after placebo administration (69%). These data by Skicon-200 and Tewameter suggest that the two plant ceramides are promising as skin-moisturizing agents not only for topical use but also for oral use.